Submission #1235652

#	Time	Username	Problem	Language	Result	Execution time	Memory
1235652		iamhereforfun	Robot (JOI21_ho_t4)	C++20	0 / 100	156 ms	14332 KiB

Main

// IamHereForFun //

#include <bits/stdc++.h>

using namespace std;

#define LSOne(X) ((X) & -(X))

const int N = 1e5 + 5;
const int M = 11;
const int L = 12;
const int LG = 25;
const int P = 37;
const int INF = 1e9 + 5;
const int MOD = 1e9 + 7;
const int nx[] = {0, -1, 0, 1}, ny[] = {-1, 0, 1, 0};

// find shortest path, for every node, calculate minimum path
// problemo: because everytime you change an edge, it affects the next node too =))
// lets say you change a edge, then you should change it so that it doesn't affect the next one =))
// but if you change a edge for another edge to be valid, then you shouldn't go to the node that it's connect too, other wise just use it
// so we use dp[N] as normal, but in your pq, you save a number indicating that the edge that leads to it is changed or not

int n, m;
long long dp[N];
vector<array<int, 3>> adj[N];
bool vis[N];

void solve()
{
    cin >> n >> m;
    for (int x = 1; x <= n; x++)
    {
        dp[x] = INF;
    }
    for (int x = 0; x < m; x++)
    {
        int a, b, c, p;
        cin >> a >> b >> c >> p;
        adj[a].push_back({b, c, p});
        adj[b].push_back({a, c, p});
    }
    priority_queue<array<long long, 3>> pq;
    dp[1] = 0;
    pq.push({0, 0, 1});
    while (!pq.empty())
    {
        array<long long, 3> arr = pq.top();
        pq.pop();
        int i = arr[2];
        if(vis[i]) continue;
        vis[i] = true;
        map<int, long long> mp;
        for(array<int, 3> a : adj[i])
        {
            if(a[0] == arr[2] && arr[1]) continue;
            mp[a[1]] += a[2];
        }
        for(array<int, 3> a : adj[i])
        {
            long long val = mp[a[1]] - a[2];
            int j = a[0];
            if(dp[j] > dp[i] + val)
            {
                dp[j] = dp[i] + val;
                pq.push({-dp[j], 0, j});
            }
            if(dp[j] > dp[i] + a[2])
            {
                dp[j] = dp[i] + a[2];
                pq.push({-dp[j], 1, j});
            }
        }
    }
    if(dp[n] == INF)
    {
        cout << -1 << "\n";
    }
    else
    {
        cout << dp[n] << "\n";
    }
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    // cin >> t;
    for (int x = 1; x <= t; x++)
    {
        solve();
    }
    return 0;
}

• Subtask 1: 0 / 34
• Subtask 2: 0 / 24
• Subtask 3: 0 / 42