silver cow party (더블릿)

#include <stdio.h>
#include <vector>
#include <queue>
 
using namespace std;
 
typedef pair<int, int> Pair;
 
priority_queue<Pair, vector<Pair>, greater<Pair> > pq;
priority_queue<Pair, vector<Pair>, greater<Pair> > pq2;
 
int main() {
    int n, m, x;
    scanf("%d %d %d", &n, &m, &x);
 
    vector<vector<Pair> > adj(n + 1);
    vector<vector<Pair> > adjR(n + 1);
 
    vector<int> visit(n + 1, 0);
    vector<int> visit2(n + 1, 0);
 
    vector<int> dist(n + 1, 30000000);
    vector<int> dist2(n + 1, 30000000);
 
    for (int i = 0; i < m; i++) {
        int v1, v2, len;
        scanf("%d %d %d", &v1, &v2, &len);
 
        adj[v1].push_back(make_pair(len, v2));
        adjR[v2].push_back(make_pair(len, v1));
    }
    
    // start->end 방향
    // Reverse!!
    pq.push(make_pair(0, x));
    visit[x] = 1;
    dist[x] = 0;
 
    while (!pq.empty()) {
        int curL = pq.top().first;
        int curV = pq.top().second;
        pq.pop();
 
        visit[curV] = 1;
 
        for (int i = 0; i < adjR[curV].size(); i++) {
            int nextV = adjR[curV][i].second;
            int nextL = adjR[curV][i].first;
 
            if (visit[nextV] == 0 && dist[nextV] > dist[curV] + nextL) {
                dist[nextV] = dist[curV] + nextL;
                pq.push(make_pair(dist[nextV], nextV));
            }
        }
    }
 
    // end->start 방향
    pq2.push(make_pair(0, x));
    dist2[x] = 0;
    visit2[x] = 1;
 
    while (!pq2.empty()) {
        int curV2 = pq2.top().second;
        int curL2 = pq2.top().first;
        pq2.pop();
 
        visit2[curV2] = 1;
        
        for (int i = 0; i < adj[curV2].size(); i++) {
            int nextV2 = adj[curV2][i].second;
            int nextL2 = adj[curV2][i].first;
        
            if (visit2[nextV2] == 0 && dist2[nextV2] > dist2[curV2] + nextL2) {
                dist2[nextV2] = dist2[curV2] + nextL2;
                pq2.push(make_pair(dist2[nextV2], nextV2));
            }
        }
    }
    
    int tmp = 0;
    for (int i = 1; i <= n; i++)
        if (tmp < dist[i] + dist2[i])
            tmp = dist[i] + dist2[i];
 
    printf("%d", tmp);
}