UVA 10803 Thunder Mountain

大意：让你求一组城镇A与B之间的最大距离，不能大于10，如果有城镇不连通，则输出Send Kurdy。

思路：Floyd

CODE：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <queue>
using namespace std;

#define MAXN 1100
#define INF 0X3F3F3F3F

struct node
{
double x, y;
}a[MAXN];

int n, m;

double d[MAXN][MAXN];

double dist(node a, node b)
{
double x1 = a.x, y1 = a.y;
double x2 = b.x, y2 = b.y;
return sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
}

void init()
{
for(int i = 1; i <= n; i++)
{
for(int j = 1; j <= n; j++)
{
if(i == j) d[i][j] = 0;
else d[i][j] = INF;
}
}
}

void Floyd()
{
double ans = -1;
for(int k = 1; k <= n; k++)
for(int i = 1; i <= n; i++)
for(int j = 1; j <= n; j++)
d[i][j] = min(d[i][j], d[i][k] + d[k][j]);
for(int i = 1; i <= n; i++)
{
for(int j = 1; j <= n; j++) if(i != j)
{
if(ans < d[i][j])
{
ans = d[i][j];
}
}
}
if(fabs(ans - INF) < 1e-4) printf("Send Kurdy\n");
else printf("%.4lf\n", ans);
}

int main()
{
int T;
scanf("%d", &T);
int times = 0;
while(T--)
{
init();
scanf("%d", &n);
for(int i = 1; i <= n; i++) scanf("%lf%lf", &a[i].x, &a[i].y);
for(int i = 1; i <= n; i++)
{
for(int j = 1; j <= n; j++) if(i != j)
{
double w = dist(a[i], a[j]);
if(w > 10) w = INF;
d[i][j] = d[j][i] = w;
}
}
printf("Case #%d:\n", ++times);
Floyd();
printf("\n");
}
return 0;
}