제출 #122950

#제출 시각아이디문제언어결과실행 시간메모리
122950arnold518Commuter Pass (JOI18_commuter_pass)C++14
100 / 100
762 ms35104 KiB
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 1e5;
const ll INF = 1e18;

int N, M, S, T, U, V;
ll DU[MAXN+10], DV[MAXN+10], DS[MAXN+10], dp[MAXN+10][2];
vector<pll> adj[MAXN+10];
vector<int> adj2[MAXN+10], revadj2[MAXN+10];

struct Queue
{
    ll v, w;
    bool operator < (const Queue& p) const { return w>p.w; }
};

void dijk(int s, ll* D)
{
    int i, j;
    for(i=1; i<=N; i++) D[i]=INF;
    priority_queue<Queue> PQ;
    PQ.push({s, 0});
    while(!PQ.empty())
    {
        Queue T=PQ.top(); PQ.pop();
        if(D[T.v]<=T.w) continue;
        D[T.v]=T.w;

        for(pii nxt : adj[T.v])
        {
            PQ.push({nxt.first, nxt.second+T.w});
        }
    }
}

bool vis[MAXN+10];
vector<int> order;
void dfs(int now)
{
    vis[now]=true;
    for(int nxt : adj2[now]) if(!vis[nxt]) dfs(nxt);
    order.push_back(now);
}

int main()
{
    int i, j;

    scanf("%d%d%d%d%d%d", &N, &M, &S, &T, &U, &V);
    for(i=1; i<=M; i++)
    {
        int u, v, w;
        scanf("%d%d%d", &u, &v, &w);
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    dijk(U, DU); dijk(V, DV); dijk(S, DS);
    for(i=1; i<=N; i++)
    {
        for(pll nxt : adj[i]) if(DS[i]+nxt.second==DS[nxt.first])
        {
            adj2[i].push_back(nxt.first);
            revadj2[nxt.first].push_back(i);
            //printf("%d ", nxt);
        }
    }

    //for(i=1; i<=N; i++) printf("U : %lld / V : %lld / S : %lld\n", DU[i], DV[i], DS[i]);

    dfs(S);
    reverse(order.begin(), order.end());

    for(int now : order)
    {
        dp[now][0]=INF; dp[now][1]=INF;
        for(int nxt : revadj2[now])
        {
            if(min(dp[nxt][0], DU[now])+min(dp[nxt][1], DV[now])<dp[now][0]+dp[now][1])
            {
                dp[now][0]=min(dp[nxt][0], DU[now]);
                dp[now][1]=min(dp[nxt][1], DV[now]);
            }
        }
        dp[now][0]=min(dp[now][0], DU[now]);
        dp[now][1]=min(dp[now][1], DV[now]);
        //printf("%d %lld %lld\n", now, dp[now][0], dp[now][1]);
    }
    printf("%lld", min(dp[T][0]+dp[T][1], DU[V]));
}

컴파일 시 표준 에러 (stderr) 메시지

commuter_pass.cpp: In function 'void dijk(int, ll*)':
commuter_pass.cpp:24:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:52:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
commuter_pass.cpp:54:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d%d%d%d", &N, &M, &S, &T, &U, &V);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commuter_pass.cpp:58:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d", &u, &v, &w);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~
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