Submission #1283012

#	Time	Username	Problem	Language	Result	Execution time	Memory
1283012		ishaanthenerd	Tracks in the Snow (BOI13_tracks)	C++20	71.56 / 100	2098 ms	79380 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1e9 + 7;
using pii = pair<int, int>;

bool in_bounds(int x, int y, int r, int c) {
    return x >= 0 && x < r && y >= 0 && y < c;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int h, w;
    cin >> h >> w;
    vector<vector<char>> grid(h, vector<char>(w, 0));
    for (int i = 0; i < h; i++) for (int j = 0; j < w; j++) cin >> grid.at(i).at(j);

    vector<vector<int>> vis(h, vector<int>(w, INT_MAX));
    for (int i = 0; i < h; i++) for (int j = 0; j < w; j++) if (grid.at(i).at(j) == '.') vis.at(i).at(j) = 0;
    vis.at(0).at(0) = 1;

    queue<pii> q;
    q.push({0, 0});
    while (!q.empty()) {
        pii p = q.front();
        q.pop();
        int x = p.first, y = p.second;
        for (int k = -2; k < 2; k++) {
            int dx = k % 2, dy = (k + 1) % 2;
            if (in_bounds(x + dx, y + dy, h, w)) {
                if (grid.at(x + dx).at(y + dy) == '.') continue;

                if (grid.at(x).at(y) == grid.at(x + dx).at(y + dy)) {
                    if (vis.at(x).at(y) < vis.at(x + dx).at(y + dy)) {
                        vis.at(x + dx).at(y + dy) = vis.at(x).at(y);
                        q.push({x + dx, y + dy});
                    }
                }
                else {
                    if (1 + vis.at(x).at(y) < vis.at(x + dx).at(y + dy)) {
                        vis.at(x + dx).at(y + dy) = 1 + vis.at(x).at(y);
                        q.push({x + dx, y + dy});
                    }
                }
            }
        }
    }

    int ans = 0;
    for (int i = 0; i < h; i++) for (int j = 0; j < w; j++) ans = max(ans, vis.at(i).at(j));
    cout << ans << endl;

    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 41.5625 / 70