Array-1 Completed

Problem1_ProductOfArrayExceptSelf.py

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+# Time Complexity : O(n) where n is the length of the array
+# Space Complexity : O(1) excluding the output array
+# Did this code successfully run on Leetcode : Yes
+# Any problem you faced while coding this : No
+
+# Approach: First pass calculates left products (product of all elements to the left of each index).
+# Second pass calculates right products and multiplies with left products to get final result.
+# This avoids division and achieves O(n) time with O(1) extra space (excluding output array).
+
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        n = len(nums)
+        result = [1] * n
+
+        # First pass: Calculate left products
+        for i in range(1, n):
+            result[i] = result[i - 1] * nums[i - 1]
+
+        # Second pass: Calculate right products and multiply with left products
+        right_product = 1
+        for i in range(n - 1, -1, -1):
+            result[i] *= right_product
+            right_product *= nums[i]
+
+        return result
+

Problem2_DiagonalTraverse.py

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+# Time Complexity : O(m * n) where m is rows and n is columns
+# Space Complexity : O(1) excluding the output array
+# Did this code successfully run on Leetcode : Yes
+# Any problem you faced while coding this : No
+
+# Approach: Traverse diagonals by tracking direction (up-right or down-left) and adjusting row/column indices.
+# When hitting boundaries, change direction and adjust indices to move to the next diagonal.
+# Continue until all elements are processed.
+
+class Solution:
+    def findDiagonalOrder(self, matrix: List[List[int]]) -> List[int]:
+        if not matrix or not matrix[0]:
+            return []
+
+        m, n = len(matrix), len(matrix[0])
+        result = []
+        row, col = 0, 0
+        direction = 1  # 1 for up-right, -1 for down-left
+
+        for _ in range(m * n):
+            result.append(matrix[row][col])
+
+            # Move in current direction
+            row -= direction
+            col += direction
+
+            # Handle boundary cases
+            if row >= m:
+                row = m - 1
+                col += 2
+                direction = -direction
+            elif col >= n:
+                col = n - 1
+                row += 2
+                direction = -direction
+            elif row < 0:
+                row = 0
+                direction = -direction
+            elif col < 0:
+                col = 0
+                direction = -direction
+
+        return result
+

Problem3_SpiralMatrix.py

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+# Time Complexity : O(m * n) where m is rows and n is columns
+# Space Complexity : O(1) excluding the output array
+# Did this code successfully run on Leetcode : Yes
+# Any problem you faced while coding this : No
+
+# Approach: Use four boundaries (top, bottom, left, right) to track the spiral traversal.
+# Traverse right, down, left, up in sequence, updating boundaries after each direction.
+# Continue until all elements are processed.
+
+class Solution:
+    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
+        if not matrix or not matrix[0]:
+            return []
+
+        m, n = len(matrix), len(matrix[0])
+        result = []
+        top, bottom, left, right = 0, m - 1, 0, n - 1
+
+        while top <= bottom and left <= right:
+            # Traverse right
+            for j in range(left, right + 1):
+                result.append(matrix[top][j])
+            top += 1
+
+            # Traverse down
+            for i in range(top, bottom + 1):
+                result.append(matrix[i][right])
+            right -= 1
+
+            # Traverse left (if still valid)
+            if top <= bottom:
+                for j in range(right, left - 1, -1):
+                    result.append(matrix[bottom][j])
+                bottom -= 1
+
+            # Traverse up (if still valid)
+            if left <= right:
+                for i in range(bottom, top - 1, -1):
+                    result.append(matrix[i][left])
+                left += 1
+
+        return result
+