Create k_smallest_matrix.py

heaps/k_smallest_matrix.py

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+# Given an n x n matrix where each of the rows and columns is sorted 
+# in ascending order, return the kth smallest element in the matrix.
+
+def kth_smallest(self, matrix, k) -> int:
+
+        n = len(matrix)
+        min_heap = []
+
+        for r in range(min(k, n)):
+
+            min_heap.append((matrix[r][0], r, 0))
+
+        heapq.heapify(min_heap)
+
+        while k:
+
+            element, r, c = heapq.heappop(min_heap)
+
+            if c < n - 1:
+                heapq.heappush(min_heap, (matrix[r][c + 1], r, c + 1))
+            
+            k -= 1
+        
+        return element