Coloring Contention

Coloring Contention 

 

 AC_Code

#include <iostream>
#include <cstdio>
#include <ctime>
#include <algorithm>
#include <string>
#include <cstring>
#include <bits/stdc++.h>
typedef long long ll;

const int maxn = 100100;
const ll INF = 1e18+9;
using namespace std;

ll x[maxn],y[maxn];
vector<pair<ll,ll> >v[maxn];
priority_queue<pair<ll,ll> >Q;
ll n,m;
ll length[maxn];

int dij(){

    ll i;
    for(i=0;i<=n;i++){
        v[i].clear();
        length[i] = INF;
    }

    for(i=1; i<=m; i++){
        v[x[i]].push_back(make_pair(y[i],1));
        v[y[i]].push_back(make_pair(x[i],1));
    }
    Q.push(make_pair(0,1));
    length[1] = 0;

    while( !Q.empty()){
        ll a, b, c, d;
        a = Q.top().second;
        b = Q.top().first;
        Q.pop();
        for( i=0;i<v[a].size(); i++){
            c = v[a][i].first;
            d = v[a][i].second;
            if( length[c]>length[a]+d ){
                length[c] = length[a]+d;
                Q.push(make_pair(-length[c],c));///优先队列从大到小排，为了从小到大排，我们存入一个负的值
            }
        }
    }
    return length[n];
}

int main()
{
    scanf("%lld%lld",&n,&m);
    for(int i=1;i<=m;i++){
        scanf("%lld%lld",&x[i],&y[i]);
    }
    ll f=dij();
    printf("%lld
",f-1);

    return 0;
}