ZOJ 2887 Server Relocation(BFS)

#include <iostream>
#include <cmath>
#include <cstdio>
#include <vector>
#include <queue>
#include <memory.h>
using namespace std;
const int maxn = 1005;

double x[maxn], y[maxn];
int s, e, n;
bool vis[maxn];
double len1, len2;

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

int bfs(){
memset(vis, 0, sizeof(vis));
queue<pair<int,int> > q;
q.push(make_pair(s, 0));
vis[s] = 1;
while (q.size()){
pair<int,int> t = q.front();
q.pop();
int u = t.first, tms = t.second;
if(u == e)return tms;
for (int i = 0; i < n; ++i){
if(!vis[i] && dis(x[u], x[i], y[u], y[i]) <= len1 + len2){
if(i == e)return tms + 1;
vis[i] = 1;
q.push(make_pair(i, tms + 1));
}
}
}
return -1;
}

int main(){
int t;
scanf("%d", &t);
while (t--){
int t2 = 0;
scanf("%d", & t2);
while (t2--){
scanf("%d %d %d %lf %lf", &n, &s, &e, &len1, &len2);
s--, e--;
for (int i = 0; i < n; ++i){
scanf("%lf %lf", &x[i], &y[i]);
}
int ans = bfs();
if(ans == -1){
printf("Impossible\n");
}else{
printf("%d\n", ans);
}
}
}
return 0;
}