HDU 1863 畅通工程——最小生成树

HDU 1863 畅通工程——最小生成树

直接用Kruskal算法求解，用cnt记录最小生成树的边数进行判断

#include #include #include #include using namespace std;const int maxn = 110;int par[maxn], ran[maxn];void init(int m) { for (int i = 0; i <= m; i++) { par[i] = i, ran[i] = 0; }}int seek(int x) { if (par[x] == x) return x; else return par[x] = seek(par[x]);}void unite(int x, int y) { x = seek(x), y = seek(y); if (x == y) return; if (ran[x] == ran[y]) par[x] = y; else { par[y] = x; if (ran[x] == ran[y]) ran[x]++; }}struct Edge { int u, v, cost; bool operator < (const Edge &another) const { return cost < another.cost; }}edge[maxn*maxn];int main(){ int m, n, u, v, cost; while (scanf("%d %d", &n, &m) == 2 && n) { for (int i = 1; i <= n; i++) { scanf("%d %d %d", &u, &v, &cost); edge[i].u = u, edge[i].v = v, edge[i].cost = cost; } sort(edge + 1, edge + 1 + n); init(m); int cnt = 0, ans = 0; for (int i = 1; i <= n; i++) { if (cnt == m - 1) break; if (seek(edge[i].u) != seek(edge[i].v)) { cnt++; ans += edge[i].cost; unite(edge[i].u, edge[i].v); } } if (cnt == m - 1) printf("%d\n", ans); else printf("?\n"); } return 0;}

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