Submission #1049530

#	Time	Username	Problem	Language	Result	Execution time	Memory
1049530		inkvizytor	Tracks in the Snow (BOI13_tracks)	C++17	86.88 / 100	1529 ms	1048576 KiB

tracks

#include <bits/stdc++.h>
using namespace std;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int h, w;
    cin >> h >> w;
    vector<string> s (h);
    cin >> s[0] >> s[1];
    vector<vector<pair<int, bool>>> g (h*w);
    for (int i = 0; i < h; i++) {
        if (i < h-2) {
            cin >> s[i+2];
        }
        for (int j = 0; j < w; j++) {
            if (s[i][j] == '.') continue;
            if (i != 0 && s[i-1][j] != '.') {
                g[i*w+j].push_back({(i-1)*w+j, s[i][j]==s[i-1][j]});
            }
            if (j != 0 && s[i][j-1] != '.') {
                g[i*w+j].push_back({i*w+j-1, s[i][j]==s[i][j-1]});
            }
            if (i != h-1 && s[i+1][j] != '.') {
                g[i*w+j].push_back({(i+1)*w+j, s[i][j]==s[i+1][j]});
            }
            if (j != w-1 && s[i][j+1] != '.') {
                g[i*w+j].push_back({i*w+j+1, s[i][j]==s[i][j+1]});
            }
        }
        if (i > 0) {
            s[i-1] = "";
        }
    }
    deque<pair<int, int>> q;
    vector<bool> odw (h*w, 0);
    q.push_back({0, 1});
    int maxd = 0;
    while (!q.empty()) {
        auto x = q.front();
        q.pop_front();
        if (odw[x.first]) {
            continue;
        }
        maxd = max(maxd, x.second);
        odw[x.first] = 1;
        for (auto i : g[x.first]) {
            if (odw[i.first]) continue;
            if (i.second) {
                q.push_front({i.first, x.second});
            }
            else {
                q.push_back({i.first, x.second+1});
            }
        }
    }
    cout << maxd << '\n';
}

• Subtask 1: 30 / 30
• Subtask 2: 56.875 / 70