Submission #1120086

#	Time	Username	Problem	Language	Result	Execution time	Memory
1120086		usacoplat	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	1031 ms	222540 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n';
const ll MOD = 1e9 + 7;
const ll MOD2 = 998244353;

char grid[4000][4000];
int dist[4000][4000];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    for (int i = 0;i < n;i++) {
        for (int j = 0;j < m;j++) {
            cin >> grid[i][j];
            dist[i][j] = 1e9;
        }
    }
    deque<array<int, 3>> q;
    q.push_back({0, 0, 1});
    while (!q.empty()) {
        array<int, 3> s = q.front();
        q.pop_front();
        dist[s[0]][s[1]] = min(s[2], dist[s[0]][s[1]]);
        if (s[0] > 0) {
            if (grid[s[0]-1][s[1]] != '.') {
                if (grid[s[0]-1][s[1]] == grid[s[0]][s[1]]) {
                    if (dist[s[0]-1][s[1]] > s[2]) {
                        q.push_front({s[0]-1, s[1], s[2]});
                    }
                } else {
                    if (dist[s[0]-1][s[1]] > s[2]+1) {
                        q.push_back({s[0]-1, s[1], s[2]+1});
                    }
                }
            }
        }
        if (s[0] < n-1) {
            if (grid[s[0]+1][s[1]] != '.') {
                if (grid[s[0]+1][s[1]] == grid[s[0]][s[1]]) {
                    if (dist[s[0]+1][s[1]] > s[2]) {
                        q.push_front({s[0]+1, s[1], s[2]});
                    }
                } else {
                    if (dist[s[0]+1][s[1]] > s[2]+1) {
                        q.push_back({s[0]+1, s[1], s[2]+1});
                    }
                }
            }
        }
        if (s[1] > 0) {
            if (grid[s[0]][s[1]-1] != '.') {
                if (grid[s[0]][s[1]-1] == grid[s[0]][s[1]]) {
                    if (dist[s[0]][s[1]-1] > s[2]) {
                        q.push_front({s[0], s[1]-1, s[2]});
                    }
                } else {
                    if (dist[s[0]][s[1]-1] > s[2]+1) {
                        q.push_back({s[0], s[1]-1, s[2]+1});
                    }
                }
            }
        }
        if (s[1] < m-1) {
            if (grid[s[0]][s[1]+1] != '.') {
                if (grid[s[0]][s[1]+1] == grid[s[0]][s[1]]) {
                    if (dist[s[0]][s[1]+1] > s[2]) {
                        q.push_front({s[0], s[1]+1, s[2]});
                    }
                } else {
                    if (dist[s[0]][s[1]+1] > s[2]+1) {
                        q.push_back({s[0], s[1]+1, s[2]+1});
                    }
                }
            }
        }
    }
    int out = 0;
    for (int i = 0;i < n;i++) {
        for (int j = 0;j < m;j++) {
            if (dist[i][j] < 1e9) {
                out = max(out, dist[i][j]);
            }
        }
    }
    cout << out << endl;
}

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