Completed Competitive Coding-1

Problem1.py

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+# Problem 1 Find Missing Number in a sorted array
+# Time Complexity: O(log N) where N denotes the number of elements in an array
+# Space Complexity: O(1)
+
+def missingNumber(arr):
+    if arr[0] != 1:
+        return 1
+    high=len(arr)-1
+    low=0
+    while low<=high:
+        mid=(low+high)//2
+        if arr[mid]==mid+1:
+            low=mid+1
+        else:
+            high=mid-1
+    return low+1
+
+
+arr=[1,2,3,4,5,7,8,9]
+print(missingNumber(arr))

Problem2.py

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+# Problem 2 Design Min Heap
+# Time Complexity: O(log N) for insert function where N is the no.of elements stored 
+#                : O(log N) for extract_min function where N is the no.of elements stored
+#                : O(1) for get_min as we are directly looking for the min value
+# Space Compelxity: O(1) as everything is happening in the same self.heap list
+
+class MinHeap:
+    def __init__(self):
+        self.heap=[]
+
+    def _heapify_up(self,index):
+        while index > 0:
+            parent_index=(index-1)//2
+            if self.heap[index]<self.heap[parent_index]:
+                self.heap[index],self.heap[parent_index]=self.heap[parent_index],self.heap[index]
+                index=parent_index
+            else:
+                break
+
+    def insert(self,val):
+        self.heap.append(val)
+        last_index=len(self.heap)-1
+        self._heapify_up(last_index)
+
+    def get_min(self):
+        return self.heap[0] if len(self.heap)>0 else None 
+
+    def _heapify_down(self,index):
+        length=len(self.heap)
+        while 2*index+1<length:
+            left_child=2*index+1
+            right_child=2*index+2
+            smallest=left_child
+
+            if right_child<length and self.heap[right_child]<self.heap[left_child]:
+                smallest=right_child
+            if self.heap[index]<=self.heap[smallest]:
+                break
+            else:
+                self.heap[index],self.heap[smallest]=self.heap[smallest],self.heap[index]
+                index=smallest
+
+    def extract_min(self):
+        if len(self.heap)==0:
+            return None
+        if len(self.heap)==1:
+            return self.heap.pop()
+        min_val=self.heap[0]
+        self.heap[0]=self.heap.pop()
+        self._heapify_down(0) 
+        return min_val
+
+
+if __name__ == "__main__":
+    my_heap = MinHeap()
+    my_heap.insert(30)
+    my_heap.insert(10)
+    my_heap.insert(20)
+    my_heap.insert(5) 
+    print("Smallest number is:", my_heap.get_min()) 
+    print("Pulling them out:")
+    print(my_heap.extract_min())
+    print(my_heap.extract_min()) 
+    print(my_heap.extract_min())
+    print(my_heap.extract_min())