POJ

建图，然后，输入的能够节省的钱，变负数存为权值，

首先按每个人都选出来算 ans 

然后用克鲁斯卡尔算法求最小生成树

得到的答案就是 最小花费了

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <string>#include <cmath>#include <set>#include <map>#include <stack>#include <queue>#include <ctype.h>#include <vector>#include <algorithm>#include <sstream>#define PI acos(-1.0)#define in freopen("in.txt", "r", stdin)#define out freopen("out.txt", "w", stdout)using namespace std;typedef long long ll;const int maxn = 100000 + 7, INF = 0x3f3f3f3f;int n, m, k, ans;int f[maxn];struct edge {    int u, v, cost;}a[maxn];bool cmp(edge a, edge b) {    return a.cost < b.cost;}void init() {    int u, v, e;    for(int i = 0; i < k; ++i) {        scanf("%d %d %d", &u, &v, &e);        a[i].u = u;        a[i].v = v+n;        a[i].cost = -1*e;    }    sort(a, a+k, cmp);    for(int i = 0; i <= (m+n); ++i)        f[i] = i;}int find_(int u) {    if(f[u] == u) return u;    return f[u] = find_(f[u]);}void kruscal() {    for(int i = 0; i < k; ++i) {        int u = find_(a[i].u), v = find_(a[i].v), cost = a[i].cost;        if(u == v) continue;        else {            f[u] = v;            ans += cost;        }    }}int main() {    int T;    scanf("%d", &T);    while(T--) {        scanf("%d %d %d", &n, &m, &k);        init();        ans = (n+m)*10000;        kruscal();        printf("%d\n", ans);    }    return 0;}