Submission #945226

#	Time	Username	Problem	Language	Result	Execution time	Memory
945226		May27_th	Robot (JOI21_ho_t4)	C++17	100 / 100	1048 ms	96200 KiB

Main

#include<bits/stdc++.h>
#define taskname "A"
using namespace std;

void World_Final();
void Solve();

int main(){
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    if (fopen(taskname".in", "r")) {
        freopen(taskname".in", "r", stdin);
        freopen(taskname".out", "w", stdout);
    }
    World_Final();
}

void World_Final(){
    int Tests = 1;
    //cin >> Tests;
    for (int i = 1; i <= Tests; i ++) {
        //cout << i << "\n";
        Solve();
    }
}

const int MAXN = 1e5 + 10;
const int64_t INF = 1e18;

int N, M;
struct Edge{ int to, c, p; };
vector<Edge> G[MAXN]; map<int, int64_t> sum[MAXN], f[MAXN];
map<int, vector<pair<int, int>>> G1[MAXN];
void Solve(){
    cin >> N >> M; for (int i = 1; i <= M; i ++) {
        int u, v, c, p; cin >> u >> v >> c >> p;
        G[u].push_back({v, c, p});
        G[v].push_back({u, c, p});
        G1[u][c].push_back({v, p});
        G1[v][c].push_back({u, p});
        sum[u][c] += p;
        sum[v][c] += p;
    } f[1][0] = 0;
    priority_queue<pair<int64_t, pair<int, int>>> pq; pq.push(make_pair(0, make_pair(1, 0)));
    while (!pq.empty()) {
        int64_t d = pq.top().first;
        int u, prevc; tie(u, prevc) = pq.top().second; pq.pop();
        if (-d != f[u][prevc]) continue;

        if (prevc) {
            for (auto [v, p] : G1[u][prevc]) {
                /// Have to flip others because haven't flipped previous edge with same
                /// color c
                if (f[v].find(0) == f[v].end() || f[v][0] > f[u][prevc] + sum[u][prevc] - p) {
                    f[v][0] = f[u][prevc] + sum[u][prevc] - p;
                    pq.push(make_pair(-f[v][0], make_pair(v, 0)));
                }
            }
        } else {
            for (auto [v, c, p] : G[u]) {
                /// Flip this edge
                if (f[v].find(0) == f[v].end() || f[v][0] > f[u][0] + p) {
                    f[v][0] = f[u][0] + p;
                    pq.push(make_pair(-f[v][0], make_pair(v, 0)));
                }

                /// Flip others
                if (f[v].find(0) == f[v].end() || f[v][0] > f[u][0] + sum[u][c] - p) {
                    f[v][0] = f[u][0] + sum[u][c] - p;
                    pq.push(make_pair(-f[v][0], make_pair(v, 0)));
                }

                /// Save to flip with latter edge
                if (f[v].find(c) == f[v].end() || f[v][c] > f[u][0]) {
                    f[v][c] = f[u][0];
                    pq.push(make_pair(-f[v][c], make_pair(v, c)));
                }
            }
        }
    }
    if (f[N].find(0) == f[N].end()) cout << -1;
    else cout << f[N][0];
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:11:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |         freopen(taskname".in", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:12:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   12 |         freopen(taskname".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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