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| #include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#define REP(i,k,n) for(int i=k;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1<<30
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
struct edge {
int from,to;
int cost;
edge(int t,int c) : to(t),cost(c) {}
edge(int f,int t,int c) : from(f),to(t),cost(c) {}
bool operator<(const edge &e) const {
return cost < e.cost;
}
};
vector<edge> G[5005];
vector<int> g[5005];
int C[5005], R[5005], d[5005];
void dijkstra(int s,int n) {
priority_queue<P,vector<P>,greater<P> > que;
fill(d,d+n,INF);
d[s] = 0;
que.push(P(0,s));
while(que.size()) {
P p = que.top();
que.pop();
int v = p.second;
if(d[v] < p.first) continue;
rep(i,G[v].size()) {
edge e = G[v][i];
if(d[e.to] > d[v] + e.cost) {
d[e.to] = d[v] + e.cost;
que.push(P(d[e.to],e.to));
}
}
}
}
int main() {
int n, m;
cin >> n >> m;
memset(C, 0, sizeof(C));
memset(R, 0, sizeof(R));
rep(i, n) cin >> C[i] >> R[i];
rep(i, m) {
int s, t;
cin >> s >> t;
s--;
t--;
g[s].push_back(t);
g[t].push_back(s);
}
rep(i, n) {
fill(d, d + n, INF);
priority_queue<P, vector<P>, greater<P> > que;
que.push(mp(0, i));
d[i] = 0;
while(que.size()) {
P p = que.top();
que.pop();
int v = p.second;
if(d[v] < p.first) continue;
rep(i, g[v].size()) {
if(d[g[v][i]] > d[v] + 1) {
d[g[v][i]] = d[v] + 1;
que.push(mp(d[v] + 1, g[v][i]));
}
}
}
rep(j, n) {
if(i == j) continue;
if(d[j] <= R[i]) {
G[i].push_back(edge(j, C[i]));
}
}
}
dijkstra(0, n);
cout << d[n-1] << endl;
return 0;
}
|