Submission #420010

#	Time	Username	Problem	Language	Result	Execution time	Memory
420010		antimirage	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	1380 ms	168612 KiB

tracks

#include <bits/stdc++.h>

#define fr first
#define sc second
#define mk make_pair
#define pb push_back

using namespace std;

const int N = 4005, A[] = {1, -1, 0, 0}, B[] = {0, 0, 1, -1};

int n, m, a[N][N], u[N][N], ans = 1, cur;

deque <pair <int, int> > q;

inline bool check(int x, int y) {
    return x >= 1 && x <= n && y >= 1 && y <= m && a[x][y] != 2 && !u[x][y];
}

int main (){
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        scanf("\n");
        for (int j = 1; j <= m; j++) {
            char ch;
            scanf("%c", &ch);
            switch (ch) {
            case 'F':
                a[i][j] = 0;
                break;
            case 'R':
                a[i][j] = 1;
                break;
            case '.':
                a[i][j] = 2;
                break;
            default:
                assert(0);
            } 
        }
    }
    cur = a[1][1];
    u[1][1] = 1;
    q.push_back({1, 1});
    
    while (!q.empty()) {
        int x = q.front().fr, y = q.front().sc;
        q.pop_front();

        
        if (a[x][y] != cur)
            ans++, cur ^= 1;
        for (int i = 0; i < 4; i++) {
            if (check(x + A[i], y + B[i])) {
                u[x + A[i]][y + B[i]] = 1;
                if (cur != a[x + A[i]][y + B[i]])
                    q.push_back({x + A[i], y + B[i]});
                else
                    q.push_front({x + A[i], y + B[i]});
            }
        }
    }
    cout << ans << endl;
}

Compilation message (stderr)

tracks.cpp: In function 'int main()':
tracks.cpp:23:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |         scanf("\n");
      |         ~~~~~^~~~~~
tracks.cpp:26:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |             scanf("%c", &ch);
      |             ~~~~~^~~~~~~~~~~

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