Submission #757667

#	Time	Username	Problem	Language	Result	Execution time	Memory
757667		drdilyor	Tracks in the Snow (BOI13_tracks)	C++17	80.31 / 100	2108 ms	1048576 KiB

tracks

#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int n, m;
    cin >> n >> m;
    vector<string> mat(n);
    for (string& s : mat) {
        cin >> s;
    }
    auto id = [m](int i, int j) { return i* m + j;};
    vector<vector<pair<int,int>>> adj(n * m);

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            for (auto [di, dj] : {pair{0, -1}, {0, 1}, {-1, 0}, {1, 0}}) {
                int ni = i + di;
                int nj = j + dj;
                if (clamp(ni, 0,n-1) == ni && clamp(nj, 0, m-1) == nj) {
                    if (mat[ni][nj] == '.' || mat[i][j] == '.') continue;
                    int c = mat[i][j] != mat[ni][nj];
                    adj[id(i, j)].push_back({id(ni, nj), c});
                }
            }
        }
    }

    vector<int> dist(n*m, -1);
    priority_queue<pair<int,int>> p;
    p.push({0, 0});
    while (p.size()) {
        auto [w, v] = p.top();
        p.pop();
        if (dist[v] != -1) continue;
        dist[v] = -w;
        for (auto [e, ew]: adj[v]) {
            if (dist[e] == -1) {
                p.push({w - ew, e});
            }
        }
    }
    cout << *max_element(dist.begin(), dist.end()) +1 << '\n';
    

    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 50.3125 / 70