251782026-02-18 11:09:34KevinBarátnők (50 pont)cpp17Elfogadva 50/50119ms9076 KiB
#include <bits/stdc++.h>
#include <climits>
#include <queue>
using namespace std;
using ll=long long;
using pll=pair<ll, ll>;
const ll MOD=1e9+7;
const ll INF=LONG_LONG_MAX;

int main() {
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    ll n, m; cin >> n >> m;
    vector<vector<pll>> graph(n, vector<pll> ());
    for (ll i=0; i<m; i++){
        ll a, b, c; cin >> a >> b >> c; a--; b--;
        graph[a].push_back({b, c});
        graph[b].push_back({a, c});
    }
    ll a, b; cin >> a >> b; a--; b--;
    vector<ll> disA(n, INF);
    vector<ll> disB(n, INF);
    vector<ll> waysA(n, 0);
    vector<ll> waysB(n, 0);
    priority_queue<pll, vector<pll>, greater<pll>> pq;
    disA[a]=0;
    waysA[a]=1;
    pq.push({0, a});
    while (pq.size()>0){
        ll disCurr=pq.top().first, idParent=pq.top().second;
        pq.pop();
        if (disCurr!=disA[idParent]) continue;
        for (auto& [idChild, road]:graph[idParent]){
            if (disA[idChild]==disCurr+road)
                waysA[idChild]=(waysA[idChild]+waysA[idParent])%MOD;
            if (disA[idChild]>disCurr+road){
                disA[idChild]=disCurr+road;
                waysA[idChild]=waysA[idParent];
                pq.push({disA[idChild], idChild});
            }
        }
    }
    disB[b]=0;
    waysB[b]=1;
    pq.push({0, b});
    while (pq.size()>0){
        ll disCurr=pq.top().first, idParent=pq.top().second;
        pq.pop();
        if (disCurr!=disB[idParent]) continue;
        for (auto& [idChild, road]:graph[idParent]){
            if (disB[idChild]==disCurr+road)
                waysB[idChild]=(waysB[idChild]+waysB[idParent])%MOD;
            if (disB[idChild]>disCurr+road){
                disB[idChild]=disCurr+road;
                waysB[idChild]=waysB[idParent];
                pq.push({disB[idChild], idChild});
            }
        }
    }
    ll total=waysA[b]*waysA[b]%MOD;
    ll bad=0;
    for (ll i=0; i<n; i++){
        if (disA[i]*2==disA[b] && disA[i]==disB[i]){
            ll curr=waysA[i]*waysB[i]%MOD;
            bad+=curr*curr%MOD;
            bad%=MOD;
        }
    }
    for (ll i=0; i<n; i++){
        for (auto& [id, road]:graph[i]){
            if (disA[i]+road==disA[id] && disA[id]+disB[id]==disA[b] && disA[i]*2<disA[b] && disA[id]*2>disA[b]){
                ll curr=waysA[i]*waysB[id]%MOD;
                bad+=curr*curr%MOD;
                bad%=MOD;
            }
        }
    }
    cout << (total-bad+MOD)%MOD;
}
RészfeladatÖsszpontTesztVerdiktIdőMemória
base50/50
1Elfogadva0/01ms316 KiB
2Elfogadva0/0115ms8680 KiB
3Elfogadva2/22ms316 KiB
4Elfogadva2/22ms316 KiB
5Elfogadva2/21ms316 KiB
6Elfogadva2/22ms316 KiB
7Elfogadva2/22ms316 KiB
8Elfogadva1/150ms5684 KiB
9Elfogadva2/286ms9076 KiB
10Elfogadva2/290ms8252 KiB
11Elfogadva2/286ms8340 KiB
12Elfogadva2/293ms8740 KiB
13Elfogadva2/298ms8244 KiB
14Elfogadva2/283ms8344 KiB
15Elfogadva2/281ms8200 KiB
16Elfogadva1/1116ms8632 KiB
17Elfogadva1/1109ms8884 KiB
18Elfogadva1/152ms5732 KiB
19Elfogadva2/2119ms8880 KiB
20Elfogadva2/2101ms8340 KiB
21Elfogadva2/2107ms8624 KiB
22Elfogadva2/2104ms8392 KiB
23Elfogadva2/2118ms8884 KiB
24Elfogadva2/281ms8208 KiB
25Elfogadva2/278ms7344 KiB
26Elfogadva2/297ms8368 KiB
27Elfogadva2/2108ms8756 KiB
28Elfogadva2/2104ms8884 KiB
29Elfogadva2/294ms8432 KiB