From 5a3e3fe5f61222879ef858124c4aae4249c01d0e Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Fri, 26 Jul 2024 20:18:20 +0700
Subject: [PATCH 01/21] Create 1.txt

---
 Topic1_Arrays/Day2207/Tung/1.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2207/Tung/1.txt

diff --git a/Topic1_Arrays/Day2207/Tung/1.txt b/Topic1_Arrays/Day2207/Tung/1.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2207/Tung/1.txt
@@ -0,0 +1 @@
+

From 186e51cf2ff1c292bd9933a62835125d45b3bfd6 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Fri, 26 Jul 2024 20:33:54 +0700
Subject: [PATCH 02/21] Update 1.txt

---
 Topic1_Arrays/Day2207/Tung/1.txt | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/Topic1_Arrays/Day2207/Tung/1.txt b/Topic1_Arrays/Day2207/Tung/1.txt
index 8b13789..3c499dc 100644
--- a/Topic1_Arrays/Day2207/Tung/1.txt
+++ b/Topic1_Arrays/Day2207/Tung/1.txt
@@ -1 +1,25 @@
+// Description: Use two Loop
+// Time complexity: O(n ^ 2)
+// Memory complexity: O(1)
+
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        vector<int> kq ;
+        for(int i = 0 ; i < nums.size() - 1 ; i++)
+        {
+            for(int j = i + 1  ; j < nums.size() ; j++)
+            {
+                if(nums[i] + nums[j] == target)
+                {
+                    kq.push_back(i);
+                    kq.push_back(j);
+                    return kq;
+                }
+            }
+        }
+        return kq;
+        
+    }
+};
 

From 6bf6a13e9ffbc448cfd5f34e840198e4905909f4 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sat, 27 Jul 2024 14:44:48 +0700
Subject: [PATCH 03/21] Create Tung

---
 Topic1_Arrays/Day2307/Tung | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2307/Tung

diff --git a/Topic1_Arrays/Day2307/Tung b/Topic1_Arrays/Day2307/Tung
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2307/Tung
@@ -0,0 +1 @@
+

From fe2962a83934293a4af22ba335e4efba266db001 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sat, 27 Jul 2024 14:45:02 +0700
Subject: [PATCH 04/21] Delete Topic1_Arrays/Day2307/Tung

---
 Topic1_Arrays/Day2307/Tung | 1 -
 1 file changed, 1 deletion(-)
 delete mode 100644 Topic1_Arrays/Day2307/Tung

diff --git a/Topic1_Arrays/Day2307/Tung b/Topic1_Arrays/Day2307/Tung
deleted file mode 100644
index 8b13789..0000000
--- a/Topic1_Arrays/Day2307/Tung
+++ /dev/null
@@ -1 +0,0 @@
-

From abde8e65a39cdc15eb15f9bd5743f561ea95b583 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sat, 27 Jul 2024 14:45:31 +0700
Subject: [PATCH 05/21] Create 1.txt

---
 Topic1_Arrays/Day2307/Tung/1.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2307/Tung/1.txt

diff --git a/Topic1_Arrays/Day2307/Tung/1.txt b/Topic1_Arrays/Day2307/Tung/1.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2307/Tung/1.txt
@@ -0,0 +1 @@
+

From 4542d594b6d769953049db447fe801a2a45c5627 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sun, 28 Jul 2024 10:37:41 +0700
Subject: [PATCH 06/21] Create 2.txt

---
 Topic1_Arrays/Day2307/Tung/2.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2307/Tung/2.txt

diff --git a/Topic1_Arrays/Day2307/Tung/2.txt b/Topic1_Arrays/Day2307/Tung/2.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2307/Tung/2.txt
@@ -0,0 +1 @@
+

From 7354fe109edd6b15984cd855dbcbe7a0bd4f0eb8 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sun, 28 Jul 2024 11:10:00 +0700
Subject: [PATCH 07/21] Update 2.txt

---
 Topic1_Arrays/Day2307/Tung/2.txt | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Topic1_Arrays/Day2307/Tung/2.txt b/Topic1_Arrays/Day2307/Tung/2.txt
index 8b13789..dfdac8d 100644
--- a/Topic1_Arrays/Day2307/Tung/2.txt
+++ b/Topic1_Arrays/Day2307/Tung/2.txt
@@ -1 +1,5 @@
-
+// Description: Use vector and loop:
++ First, Add the first element in vector intervals to the new vector;
++ Second, Use loop and check the case to save result 
+// Time memory: O (n log(n))
+// 

From 5847f5283f480e7cded185e09497188b815d964d Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sun, 28 Jul 2024 11:11:44 +0700
Subject: [PATCH 08/21] Update 2.txt

---
 Topic1_Arrays/Day2307/Tung/2.txt | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/Topic1_Arrays/Day2307/Tung/2.txt b/Topic1_Arrays/Day2307/Tung/2.txt
index dfdac8d..3aa011d 100644
--- a/Topic1_Arrays/Day2307/Tung/2.txt
+++ b/Topic1_Arrays/Day2307/Tung/2.txt
@@ -1,5 +1,29 @@
 // Description: Use vector and loop:
 + First, Add the first element in vector intervals to the new vector;
 + Second, Use loop and check the case to save result 
-// Time memory: O (n log(n))
-// 
+// Time complexity: O (n log(n))
+// Memory complexity: O (n)
+class Solution {
+public:
+    vector<vector<int>> merge(vector<vector<int>>& intervals) {
+        sort(intervals.begin() , intervals.end());
+
+        vector<vector<int>> merge;
+
+        merge.push_back(intervals[0]);
+        
+        for(int i = 1 ; i < intervals.size() ; i++)
+        {
+            if(merge.back()[1] >= intervals[i][0])
+            {
+                merge.back()[1] = max(merge.back()[1] , intervals[i][1]);
+            }
+            else
+            {
+                merge.push_back(intervals[i]);
+            }
+        }
+        return merge;
+        
+    }
+};

From e3f1f0cc46e360f94234935189c6a12762d767a3 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sun, 28 Jul 2024 11:41:21 +0700
Subject: [PATCH 09/21] Create 3.txt

---
 Topic1_Arrays/Day2307/Tung/3.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2307/Tung/3.txt

diff --git a/Topic1_Arrays/Day2307/Tung/3.txt b/Topic1_Arrays/Day2307/Tung/3.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2307/Tung/3.txt
@@ -0,0 +1 @@
+

From 16d254027a32c2374d3392d961c1819e92770a6b Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Sun, 28 Jul 2024 11:45:39 +0700
Subject: [PATCH 10/21] Update 3.txt

---
 Topic1_Arrays/Day2307/Tung/3.txt | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/Topic1_Arrays/Day2307/Tung/3.txt b/Topic1_Arrays/Day2307/Tung/3.txt
index 8b13789..a24bbc5 100644
--- a/Topic1_Arrays/Day2307/Tung/3.txt
+++ b/Topic1_Arrays/Day2307/Tung/3.txt
@@ -1 +1,27 @@
-
+// Desciption: Use loop :
++ if prices[i] > price-min . Update price_min = prices[i]. Else update result.
+// Time complexity: O(n)
+// Memory complexity: O(1)
+class Solution {
+public:
+    int maxProfit(vector<int>& prices) {
+        if(prices.size() == 1)
+        {
+            return 0;
+        }
+        int price_min = prices[0];
+        int result  = 0;
+        for(int i = 0 ; i < prices.size() ; i++)
+        {
+            if(price_min > prices[i])
+            {
+                price_min = prices[i];
+            }
+            else
+            {
+                result = max(result , prices[i] - price_min);
+            }
+        }
+        return result;
+    }
+};

From 213c228dd121e27ee6653a3993c369702293ac9f Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 18:32:52 +0700
Subject: [PATCH 11/21] Create 1.txt

---
 Topic1_Arrays/Day2407/Tung/1.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2407/Tung/1.txt

diff --git a/Topic1_Arrays/Day2407/Tung/1.txt b/Topic1_Arrays/Day2407/Tung/1.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2407/Tung/1.txt
@@ -0,0 +1 @@
+

From 28b61823be0b493c9a09af7f275dae8b00358012 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 18:37:23 +0700
Subject: [PATCH 12/21] Update 1.txt

---
 Topic1_Arrays/Day2407/Tung/1.txt | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Topic1_Arrays/Day2407/Tung/1.txt b/Topic1_Arrays/Day2407/Tung/1.txt
index 8b13789..136a129 100644
--- a/Topic1_Arrays/Day2407/Tung/1.txt
+++ b/Topic1_Arrays/Day2407/Tung/1.txt
@@ -1 +1,23 @@
+// Description: Use map and loop :
++ First: count char of stings.
++ Solve:
+// Time complexity: O(n * k log(k))
+// Memory complexity: O(n * k)
+class Solution {
+public:
+    vector<vector<string>> groupAnagrams(vector<string>& strs) {
+        map<string, vector<string> >mp;
 
+        for(auto str:strs){
+            string s = str;
+            sort(s.begin(), s.end());
+            mp[s].push_back(str);
+        }
+
+        vector<vector<string>> ans;
+        for(auto it = mp.begin(); it != mp.end(); it++){
+            ans.push_back(it->second);
+        }
+        return ans;
+    }
+};

From f25c38480227e9b2df088aadb278c6277565b2c1 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 18:37:45 +0700
Subject: [PATCH 13/21] Create 2.txt

---
 Topic1_Arrays/Day2407/Tung/2.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2407/Tung/2.txt

diff --git a/Topic1_Arrays/Day2407/Tung/2.txt b/Topic1_Arrays/Day2407/Tung/2.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2407/Tung/2.txt
@@ -0,0 +1 @@
+

From 4563e3248af3e998528fb08aedeed6621bcf633c Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 18:54:21 +0700
Subject: [PATCH 14/21] Update 2.txt

---
 Topic1_Arrays/Day2407/Tung/2.txt | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/Topic1_Arrays/Day2407/Tung/2.txt b/Topic1_Arrays/Day2407/Tung/2.txt
index 8b13789..be0b820 100644
--- a/Topic1_Arrays/Day2407/Tung/2.txt
+++ b/Topic1_Arrays/Day2407/Tung/2.txt
@@ -1 +1,19 @@
-
+// Description: Use priority_queue and do it have't more k elements.
+// Time complexity: O(n * log(k)).
+// Memory complexity: O(k).
+class Solution {
+public:
+    int findKthLargest(vector<int>& nums, int k) {
+        priority_queue<int , vector<int> , greater<int>> pq;
+        for(int i = 0 ; i < nums.size() ; i++)
+        {
+            pq.push(nums[i]);
+            if(pq.size() > k)
+            {
+                pq.pop();
+            }
+        }
+        return pq.top();
+        return 0;
+    }
+};

From 26d58a58a06821433905a675e76ec399673d3df9 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 18:54:36 +0700
Subject: [PATCH 15/21] Create 3.txt

---
 Topic1_Arrays/Day2407/Tung/3.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2407/Tung/3.txt

diff --git a/Topic1_Arrays/Day2407/Tung/3.txt b/Topic1_Arrays/Day2407/Tung/3.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2407/Tung/3.txt
@@ -0,0 +1 @@
+

From d29ff899f9290ccae310d678d38d1b69ec804529 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 19:15:19 +0700
Subject: [PATCH 16/21] Update 3.txt

---
 Topic1_Arrays/Day2407/Tung/3.txt | 41 ++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/Topic1_Arrays/Day2407/Tung/3.txt b/Topic1_Arrays/Day2407/Tung/3.txt
index 8b13789..b3195d0 100644
--- a/Topic1_Arrays/Day2407/Tung/3.txt
+++ b/Topic1_Arrays/Day2407/Tung/3.txt
@@ -1 +1,42 @@
+// Description: Use pointer left and right.
+// Time complexity: O(n ^ 2)
+// Memory complexity: O(k)
+class Solution {
+public:
+    vector<vector<int>> threeSum(vector<int>& nums) {
+        vector<vector<int>> result;
+        sort(nums.begin(), nums.end());
+        int n = nums.size();
 
+        for (int i = 0; i < n - 2; ++i) {
+            if (i > 0 && nums[i] == nums[i - 1]) {
+                continue;
+            }
+
+            int left = i + 1;
+            int right = n - 1;
+
+            while (left < right) {
+                int sum = nums[i] + nums[left] + nums[right];
+                if (sum == 0) {
+                    result.push_back({nums[i], nums[left], nums[right]});
+                    
+                    while (left < right && nums[left] == nums[left + 1]) {
+                        ++left;
+                    }
+                    while (left < right && nums[right] == nums[right - 1]) {
+                        --right;
+                    }
+                    ++left;
+                    --right;
+                } else if (sum < 0) {
+                    ++left;
+                } else {
+                    --right;
+                }
+            }
+        }
+
+        return result;
+    }
+};

From 349bb9b0bd0bcdc0e6d4375d30fea14457658424 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 19:41:33 +0700
Subject: [PATCH 17/21] Create 1.txt

---
 Topic1_Arrays/Day2507/Tung/1.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2507/Tung/1.txt

diff --git a/Topic1_Arrays/Day2507/Tung/1.txt b/Topic1_Arrays/Day2507/Tung/1.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2507/Tung/1.txt
@@ -0,0 +1 @@
+

From 8594a1a034ec7755898fd184f4bdcb3d8a985032 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 19:43:58 +0700
Subject: [PATCH 18/21] Update 1.txt

---
 Topic1_Arrays/Day2507/Tung/1.txt | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/Topic1_Arrays/Day2507/Tung/1.txt b/Topic1_Arrays/Day2507/Tung/1.txt
index 8b13789..9fb46bc 100644
--- a/Topic1_Arrays/Day2507/Tung/1.txt
+++ b/Topic1_Arrays/Day2507/Tung/1.txt
@@ -1 +1,27 @@
-
+// Description: Use pointer left and right.
+// Time complexity: O(n).
+// Memory complexity: O(1).
+class Solution {
+public:
+    int maxArea(vector<int>& height) {
+        int result = 0;
+        int left = 0 ; 
+        int right = height.size()-1;
+        while(left < right )
+        {
+            int height_c = min(height[left] , height[right]);
+            int wight = right - left;
+            int area = wight * height_c;
+            result = max(result , area);
+            if(height[left] < height[right])
+            {
+                left++;
+            } 
+            else
+            {
+                right--;
+            }
+        }
+        return result;
+    }
+};

From 6a5790ec9663c6ed5b6486e7fe01d61237ced6b9 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 20:09:26 +0700
Subject: [PATCH 19/21] Create 2.txt

---
 Topic1_Arrays/Day2507/Tung/2.txt | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Topic1_Arrays/Day2507/Tung/2.txt

diff --git a/Topic1_Arrays/Day2507/Tung/2.txt b/Topic1_Arrays/Day2507/Tung/2.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/Topic1_Arrays/Day2507/Tung/2.txt
@@ -0,0 +1 @@
+

From d4aa29d0a37bc0302d603777ce86f797aa1e85ff Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Mon, 29 Jul 2024 20:19:31 +0700
Subject: [PATCH 20/21] Update 2.txt

---
 Topic1_Arrays/Day2507/Tung/2.txt | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/Topic1_Arrays/Day2507/Tung/2.txt b/Topic1_Arrays/Day2507/Tung/2.txt
index 8b13789..c847ffc 100644
--- a/Topic1_Arrays/Day2507/Tung/2.txt
+++ b/Topic1_Arrays/Day2507/Tung/2.txt
@@ -1 +1,33 @@
+// Description: Use  unordered_map.
+// Time complexity: O(n).
+// Memory complexity: O(n).
+#include <vector>
+#include <unordered_map>
+using namespace std;
 
+class Solution {
+public:
+    int subarraySum(vector<int>& nums, int k) {
+        unordered_map<int, int> prefixSumCount; 
+        int sum = 0; 
+        int result = 0; 
+        
+        prefixSumCount[0] = 1;
+        
+        for (int num : nums) {
+            sum += num; 
+            if (prefixSumCount.find(sum - k) != prefixSumCount.end()) {
+
+                result += prefixSumCount[sum - k];
+            }
+            prefixSumCount[sum]++;
+        }
+        
+        return result;
+    }
+};
+
+
+In another case: use 2 loop:
+// Time complexity: O(n ^ 2).
+// Memory complexity: O(1).

From 3da85c1820e0690da37920ff20cb828766d59d75 Mon Sep 17 00:00:00 2001
From: Tungcutenhoem <160585498+Tungcutenhoem@users.noreply.github.com>
Date: Tue, 30 Jul 2024 17:17:17 +0700
Subject: [PATCH 21/21] Create 3.txt

---
 Topic1_Arrays/Day2507/Tung/3.txt | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 Topic1_Arrays/Day2507/Tung/3.txt

diff --git a/Topic1_Arrays/Day2507/Tung/3.txt b/Topic1_Arrays/Day2507/Tung/3.txt
new file mode 100644
index 0000000..01571fd
--- /dev/null
+++ b/Topic1_Arrays/Day2507/Tung/3.txt
@@ -0,0 +1,31 @@
+// Description: Use ASCII and count fred of alphal.
+// Time complexity: O(n * m).
+// Memory complexity: O(n * m).
+class Solution {
+public:
+    vector<string> commonChars(vector<string>& words) {
+        vector<string> result;
+        vector<int> min_fred(26 , 1000);
+        for(string word : words)
+        {
+            vector<int> fred(26 , 0);
+            for(char c : word)
+            {
+                fred[c - 'a']++;
+            }
+            for(int i = 0 ; i < 26 ; i++)
+            {
+                min_fred[i] = min(min_fred[i] , fred[i]);
+            }
+        }
+        for(int i = 0 ; i < 26 ; i++)
+        {
+            while(min_fred[i] > 0)
+            {
+                result.push_back(string(1 , 'a' + i));
+                min_fred[i]--;
+            }
+        }
+        return result;
+    }
+};