Mar 20

Author: siddydutta

2025-03-March-LeetCoding-Challenge/Minimum Cost Walk in Weighted Graph.py

@@ -0,0 +1,52 @@
+class UnionFind:
+    def __init__(self, n: int):
+        self.parent = list(range(n))
+        self.rank = [0] * n
+        self.weights = [-1] * n
+
+    def find(self, x: int) -> int:
+        if x != self.parent[x]:
+            self.parent[x] = self.find(self.parent[x])
+        return self.parent[x]
+
+    def union(self, x: int, y: int, weight: int) -> None:
+        xx, yy = self.find(x), self.find(y)
+        if self.rank[xx] < self.rank[yy]:
+            self.parent[xx] = yy
+        else:
+            self.parent[yy] = xx
+
+        self.weights[xx] = self.weights[yy] = self.weights[xx] & self.weights[yy] & weight
+        if self.rank[xx] == self.rank[yy]:
+            self.rank[xx] += 1
+
+    def minimum_cost_of_walk(self, x: int, y: int) -> int:
+        if x == y:
+            return 0
+        if self.find(x) != self.find(y):
+            return -1
+        return self.weights[self.find(x)]
+
+
+class Solution:
+    def minimumCost(self, n: int, edges: list[list[int]], query: list[list[int]]) -> list[int]:
+        uf = UnionFind(n)
+        for u, v, w in edges:
+            uf.union(u, v, w)
+        return [uf.minimum_cost_of_walk(u, v) for u, v in query]
+
+
+def main():
+    n = 5
+    edges = [[0, 1, 7], [1, 3, 7], [1, 2, 1]]
+    query = [[0, 3], [3, 4]]
+    assert Solution().minimumCost(n, edges, query) == [1, -1]
+
+    n = 3
+    edges = [[0, 2, 7], [0, 1, 15], [1, 2, 6], [1, 2, 1]]
+    query = [[1, 2]]
+    assert Solution().minimumCost(n, edges, query) == [0]
+
+
+if __name__ == '__main__':
+    main()

2025-03-March-LeetCoding-Challenge/README.md

@@ -23,7 +23,7 @@
 | March 17 | [2206. Divide Array Into Equal Pairs](https://leetcode.com/problems/divide-array-into-equal-pairs/) | Easy | Solved |
 | March 18 | [2401. Longest Nice Subarray](https://leetcode.com/problems/longest-nice-subarray/) | Medium | Unsolved |
 | March 19 | [3191. Minimum Operations to Make Binary Array Elements Equal to One I](https://leetcode.com/problems/minimum-operations-to-make-binary-array-elements-equal-to-one-i/) | Medium | Solved |
-| March 20 | []() |  |  |
+| March 20 | [3108. Minimum Cost Walk in Weighted Graph](https://leetcode.com/problems/minimum-cost-walk-in-weighted-graph/) | Hard | Unsolved |
 | March 21 | []() |  |  |
 | March 22 | []() |  |  |
 | March 23 | []() |  |  |
@@ -42,4 +42,4 @@
 | ---    | --- | --- | --- |
 | Easy   | 6 | 6 | 0 |
 | Medium | 13 | 6 | 7 |
-| Hard   | 0 | 0 | 0 |
+| Hard   | 1 | 0 | 1 |