【HDU1875】畅通工程再续（MST基础题）

更改成实形数即可。第一次敲完直接交，CE了一次。晕。

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstdio>
#include <cctype>
#include <cmath>
#include <algorithm>
#include <numeric>

#define typec double
using namespace std;

const typec inf = 0xffff;
const int V = 1005;
int vis[V];
typec lowc[V], Map[V][V], point[V][2];

typec prim (typec cost[][V], int n) {
    int i, j, p;
    typec minc, res = 0;
    memset(vis, 0, sizeof(vis));
    vis[0] = 1;
    for (i = 1; i < n; ++ i) lowc[i] = cost[0][i];
    for (i = 1; i < n; ++ i) {
        minc = inf; p = -1;
        for (j = 0; j < n; ++ j ) {
            if (0 == vis[j] && minc > lowc[j]) {
                minc = lowc[j];
                p = j;
            }
        }
        if (inf == minc) return -1;
        res += minc;
        vis[p] = 1;
        for (j = 0; j < n; ++ j) {
            if (0 == vis[j] && lowc[j] > cost[p][j]) {
                lowc[j] = cost[p][j];
            }
        }
    }
    return res;
}

double cal_dis (double x1, double y1, double x2, double y2) {
    return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}

int main () {
    int T; scanf("%d", &T);
    while (T --) {
        //vector<pair<double, double> > p;
        int n; scanf("%d", &n);
        for (int i = 0; i < n; ++ i) {
            scanf("%lf%lf", &point[i][0], &point[i][1]);
        }

        for (int i = 0 ; i < 105; ++ i) {
            for (int j = 0; j < 105; ++ j) {
                if (i == j) Map[i][j] = 0;
                else Map[i][j] = inf;
            }
        }

        for (int i = 0; i < n; ++i) {
            for (int j = i + 1; j < n; ++ j) {
                double w = cal_dis(point[i][0], point[i][1],point[j][0],point[j][1]);
                if (w >= 10 && w <= 1000)
                    Map[i][j] = Map[j][i] = min(Map[i][j], w);
                else continue;
                /*cout << Map[i][j] << endl;
                cout << Map[j][i] << endl;*/
            }
        }

        /*for (int i = 0; i < 2; ++ i) {
            for (int j = 0 ; j < 2; ++ j) {
                cout << Map[i][j] << " ";
            }
            cout << endl;
        }*/
        double ans = 100 * prim(Map, n);
        if (ans > 0)
            printf("%.1lf
", ans);
        else {
            printf("oh!
");
        }
        //cout << prim (Map, n) << endl;
    }
    return 0;
}