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Author: lmizner

Two_Heaps/find_right_interval.py

@@ -0,0 +1,61 @@
+import heapq
+
+def find_right_interval(intervals):
+
+    # Initialize result array
+    result = [-1] * len(intervals)
+
+    # Initialize min_heaps for start and end points
+    start_heap = []
+    end_heap = []
+
+    # Populate heaps with intervals
+    for i, interval in enumerate(intervals):
+        heapq.heappush(start_heap, (interval[0], i))
+        heapq.heappush(end_heap, (interval[1], i))
+
+    # Process each interval based on its end point
+    while end_heap:
+
+        # Get the interval with the smallest end point
+        value, index = heapq.heappop(end_heap)
+
+        # Remove all start points from that are smaller than current end point
+        while start_heap and start_heap[0][0] < value:
+            heapq.heappop(start_heap)
+
+        # If start heap is not empty, top element is smallest valid interval
+        if start_heap:
+            result[index] = start_heap[0][1]
+
+    # Return result list
+    return result
+
+
+
+# Time Complexity = O(nlogn)
+# Space Complexity = O(n)
+
+
+
+###############################################################
+
+
+
+def main():
+    test_cases = [
+        [[1, 2]],
+        [[3, 4], [2, 3], [1, 2]],
+        [[1, 4], [2, 3], [3, 4]],
+        [[5, 6], [1, 2], [3, 4]],
+        [[1, 3], [2, 4], [3, 5], [4, 6]],
+    ]
+
+    for i, test_case in enumerate(test_cases):
+        print(i + 1, "\tintervals:", test_case)
+        result = find_right_interval(test_case)
+        print("\n\tOutput:", result)
+        print("-" * 100)
+
+if __name__ == "__main__":
+    main()