diff --git a/Problem1.py b/Problem1.py
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index 00000000..1ab105f4
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+++ b/Problem1.py
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+"""
+TC: O(logN) {Used binary search to eliminate the search space by half, if the index + 1 == number at that index, we know the left part is sorted}
+SC: O(1) {No extra space is used here}
+
+Approach:
+
+We use two pointers for our Binary search and reduce the search space by half if we dont find any discrepancy, i.e. if the index + 1 matches the number at that index.
+
+The problem ran successfully on GeeksForGeeks
+"""
+def missingNumber(arr):
+    n = len(arr)
+
+    left, right = 0, n - 1
+    
+    while left < right:
+      mid = left + (right - left)//2
+      
+      if arr[mid] == mid + 1:
+        left = mid + 1
+      elif arr[mid] > mid + 1:
+        right = mid 
+    return left + 1
+
+if __name__ == "__main__":
+    arr = [1, 2, 3, 4, 5, 6, 8, 9]
+    print(missingNumber(arr))
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