uva10803

题目链接请戳 这里

 

解题思路

直接用floyd就行了。再求最大值。

 

代码

#include<stdio.h>
#include<math.h>
#include<string.h>
#include<algorithm>
#define N 1040
#define INF 1e9
using namespace std;

int x[N], y[N];
double d[N][N], ans;
int n;

double get_len(int a, int b)
{
    return sqrt(pow(x[a] - x[b], 2) + pow(y[a] - y[b], 2));
}

void floyd()
{
    for (int k = 0; k < n; k++)
        for (int i = 0; i < n; i++) 
            for (int j = 0; j < n; j++) if (d[i][k] < INF && d[k][j] < INF)
                d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
}

bool get_ans()
{
    ans = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++) if (i != j)
            ans = max(ans, d[i][j]);
    if (ans == INF)
        return false;
    else 
        return true;
}

int main()
{
    int tests = 0, t, c;
    scanf("%d", &c);
    while (c--) {
        tests++;
        scanf("%d", &n);
        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++) d[i][j] = (i == j) ? 0 : INF;
        for (int i = 0; i < n; i++)
            scanf("%d%d", &x[i], &y[i]);
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n; j++) 
                if (get_len(i, j) > 10.0)
                    d[i][j] = d[j][i] = INF;
                else 
                    d[i][j] = d[j][i] = get_len(i, j);
        floyd();
        printf("Case #%d:\n", tests);
        if (get_ans()) 
            printf("%.4lf\n", ans);
        else 
            printf("Send Kurdy\n");
        printf("\n");
    }
    return 0;
}