From 23741c95f56c3237c55b06d60821fe4b029c62ba Mon Sep 17 00:00:00 2001
From: dipanjal <dipanjalmaitra@gmail.com>
Date: Sat, 23 Aug 2025 23:12:29 +0600
Subject: [PATCH 1/4] word break bruteforce solution

---
 leetcode/dp/Word_Break/recursion.py | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 leetcode/dp/Word_Break/recursion.py

diff --git a/leetcode/dp/Word_Break/recursion.py b/leetcode/dp/Word_Break/recursion.py
new file mode 100644
index 0000000..a4606b9
--- /dev/null
+++ b/leetcode/dp/Word_Break/recursion.py
@@ -0,0 +1,27 @@
+# Recursive bruteforce solution
+# TC: O(2^n)
+# SC: stack: O(n) + set: O(m) where m = number of words
+class Solution:
+    def wordBreak(self, s: str, wordDict: List[str]) -> bool:
+        wordSet = set(wordDict)
+
+        maxLen = 0
+        for word in wordSet:
+            maxLen = max(maxLen, len(word))
+
+        def canBreak(start: int, end: int) -> bool:
+            if end == len(s) - 1:
+                return s[start:end+1] in wordSet
+            
+            # exceeded the max window limit but we couldn't break
+            if (end - start) + 1 > maxLen:
+                return False
+
+            
+            not_match = canBreak(start, end+1)
+            match = False
+            if s[start:end+1] in wordSet:
+                match = canBreak(start=end+1, end=end+1)
+            return match or not_match
+        
+        return canBreak(0, 0)
\ No newline at end of file

From e3db725b472acb394e5e769ad312152185701333 Mon Sep 17 00:00:00 2001
From: dipanjal <dipanjalmaitra@gmail.com>
Date: Sat, 23 Aug 2025 23:17:25 +0600
Subject: [PATCH 2/4] LC:139: word break memoized solution

---
 leetcode/dp/Word_Break/memoization.py | 32 +++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 leetcode/dp/Word_Break/memoization.py

diff --git a/leetcode/dp/Word_Break/memoization.py b/leetcode/dp/Word_Break/memoization.py
new file mode 100644
index 0000000..9ebe216
--- /dev/null
+++ b/leetcode/dp/Word_Break/memoization.py
@@ -0,0 +1,32 @@
+# Recursive bruteforce solution
+# TC: O(n)
+# SC: stack: O(n) + set: O(n)
+class Solution:
+    def wordBreak(self, s: str, wordDict: List[str]) -> bool:
+        wordSet = set(wordDict)  # O(1)
+        n = len(s)
+
+        # unique combo: n * n -> O(n*n)
+        # memo: [n] * [n] -> O(n*n)
+        memo = [[-1] * n for _ in range(n)]
+
+        def canBreak(start: int, end: int) -> bool:
+            # is it an overlapping sub
+            if memo[start][end] != -1:
+                return memo[start][end]
+
+            # base case
+            if end == n-1:
+                memo[start][end] = s[start:end+1] in wordSet
+                return memo[start][end]
+            
+            # expanding the window
+            not_match = canBreak(start, end+1)
+            match = False
+            if s[start:end+1] in wordSet:
+                match = canBreak(start=end+1, end=end+1)
+            
+            memo[start][end] = not_match or match
+            return memo[start][end]
+        
+        return canBreak(0, 0)
\ No newline at end of file

From 8676e853f5419aeb2b0e89466b42270200ec3142 Mon Sep 17 00:00:00 2001
From: dipanjal <dipanjalmaitra@gmail.com>
Date: Sat, 23 Aug 2025 23:18:00 +0600
Subject: [PATCH 3/4] LC:139: word break tabulation solution

---
 leetcode/dp/Word_Break/tabulation.py | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 leetcode/dp/Word_Break/tabulation.py

diff --git a/leetcode/dp/Word_Break/tabulation.py b/leetcode/dp/Word_Break/tabulation.py
new file mode 100644
index 0000000..5752bd1
--- /dev/null
+++ b/leetcode/dp/Word_Break/tabulation.py
@@ -0,0 +1,23 @@
+# Recursive bruteforce solution
+# TC: O(n)
+# SC: set: O(n) + memo: O(n^2)
+class Solution:
+    def wordBreak(self, s: str, wordDict: List[str]) -> bool:
+        wordSet = set(wordDict)  # O(1)
+        n = len(s)
+
+        memo = [[False] * n for _ in range(n)]
+        # start => col
+        # end => row
+        for start in range(n):
+            memo[n-1][start] = s[start:n] in wordSet
+        
+        for end in range(n-2, -1, -1):
+            for start in range(n):
+                not_match = memo[end+1][start] # canBreak(start, end+1)
+                match = False
+                if s[start:end+1] in wordSet:
+                    match = memo[end+1][end+1] # canBreak(start=end+1, end=end+1)
+                memo[end][start] = not_match or match
+
+        return memo[0][0]
\ No newline at end of file

From b24d3a5e5d3dba2db0576db5beae6f4b5f1ab07e Mon Sep 17 00:00:00 2001
From: dipanjal <dipanjalmaitra@gmail.com>
Date: Sat, 23 Aug 2025 23:18:35 +0600
Subject: [PATCH 4/4] LC:139: word break space optimized

---
 leetcode/dp/Word_Break/space_optimization.py | 26 ++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 leetcode/dp/Word_Break/space_optimization.py

diff --git a/leetcode/dp/Word_Break/space_optimization.py b/leetcode/dp/Word_Break/space_optimization.py
new file mode 100644
index 0000000..333836d
--- /dev/null
+++ b/leetcode/dp/Word_Break/space_optimization.py
@@ -0,0 +1,26 @@
+# Recursive bruteforce solution
+# TC: O(n)
+# SC: set: O(n) + memo: O(n) + O(n) ~ O(n)
+class Solution:
+    def wordBreak(self, s: str, wordDict: List[str]) -> bool:
+        wordSet = set(wordDict)  # O(1)
+        n = len(s)
+        
+        # start => col
+        # end => row
+        next_row = [False] * n
+        for start in range(n):
+            next_row[start] = s[start:n] in wordSet
+        
+        # end=3
+        for end in range(n-2, -1, -1):
+            curr = [False] * n
+            for start in range(n):
+                not_match = next_row[start]  # canBreak(start, end+1)
+                match = False
+                if s[start:end+1] in wordSet:
+                    match = next_row[end+1]  # canBreak(start=end+1, end=end+1)
+                curr[start] = not_match or match
+            next_row = curr
+
+        return next_row[0]
\ No newline at end of file