go: add «3108. Minimum Cost Walk in Weighted Graph»

URL:	https://leetcode.com/problems/minimum-cost-walk-in-weighted-graph/
Signed-off-by: Matej Focko <me@mfocko.xyz>

go/minimum-cost-walk-in-weighted-graph.go

@@ -0,0 +1,76 @@
+package main
+
+type Edge struct {
+	v      int
+	weight int
+}
+
+type Component struct {
+	id   int
+	cost int
+}
+
+func minimumCost(n int, edges, query [][]int) []int {
+	// reconstruct graph
+	makeGraph := func() [][]Edge {
+		g := make([][]Edge, n)
+		for _, edge := range edges {
+			u, v, weight := edge[0], edge[1], edge[2]
+
+			g[u] = append(g[u], Edge{v: v, weight: weight})
+			g[v] = append(g[v], Edge{v: u, weight: weight})
+		}
+
+		return g
+	}
+	g := makeGraph()
+
+	visited := make([]bool, n)
+	components := make([]int, n)
+	costs := make([]int, 0)
+
+	var getCost func(int, int) int
+	getCost = func(id, u int) int {
+		cost := int((^uint(0)) >> 1)
+
+		components[u] = id
+		visited[u] = true
+
+		for _, edge := range g[u] {
+			cost &= edge.weight
+
+			if visited[edge.v] {
+				continue
+			}
+
+			cost &= getCost(id, edge.v)
+		}
+
+		return cost
+	}
+
+	// traverse components
+	componentId := 0
+	for u := range n {
+		if visited[u] {
+			continue
+		}
+
+		costs = append(costs, getCost(componentId, u))
+		componentId++
+	}
+
+	// construct answer to queries
+	answer := make([]int, len(query))
+	for i, q := range query {
+		start, end := q[0], q[1]
+
+		if components[start] == components[end] {
+			answer[i] = costs[components[start]]
+		} else {
+			answer[i] = -1
+		}
+	}
+
+	return answer
+}