POJ 1258 Agri-Net

最小生成树
kruskal算法

#include <cstdio>#include <cstring>#include <algorithm>#include <vector>using namespace std;#define N 1002struct node {    int u, v, w;    node() {}    node(int _u, int _v, int _w):u(_u), v(_v), w(_w) {}};vector<node> edge;int n,f[N];bool cmp(const node &x, const node &y) {    return x.w < y.w;}int find_set(int x) {    if (f[x] == x) return x;    return f[x] = find_set(f[x]);}int Kruskal() {    sort(edge.begin(), edge.end(), cmp);    for (int i=1; i<=n; i++) f[i] = i;    int ans = 0;    for (int i=0, u, v, w; i<edge.size(); i++) {        u = edge[i].u, v = edge[i].v, w = edge[i].w;        u = find_set(u), v = find_set(v);        if (u == v) continue;        f[u] = v;        ans += w;    }    return ans;}int main() {    while (scanf("%d", &n) == 1) {        edge.clear();        for(int i = 1; i <= n; i++)        {            for(int j = 1; j <= n; j++)            {                int c;                scanf("%d",&c);                if(i == j) c = 0x7fffffff;                edge.push_back(node(i, j, c));                edge.push_back(node(j, i, c));            }        }        printf("%d\n", Kruskal());    }    return 0;}