Leetcode/leetcode1559.cpp at main · ksaini-web/Leetcode · GitHub

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class Solution {
public:
    int m, n;
    vector<vector<int>> vis;

    int dx[4] = {1, -1, 0, 0};
    int dy[4] = {0, 0, 1, -1};

    bool dfs(int r, int c, int pr, int pc, vector<vector<char>>& grid) {
        vis[r][c] = 1;

        for (int k = 0; k < 4; k++) {
            int nr = r + dx[k];
            int nc = c + dy[k];

            if (nr < 0 || nc < 0 || nr >= m || nc >= n) continue;
            if (grid[nr][nc] != grid[r][c]) continue;

            if (!vis[nr][nc]) {
                if (dfs(nr, nc, r, c, grid)) return true;
            }
            else {
                if (nr != pr || nc != pc) {
                    return true;
                }
            }
        }

        return false;
    }

    bool containsCycle(vector<vector<char>>& grid) {
        m = grid.size();
        n = grid[0].size();

        vis.assign(m, vector<int>(n, 0));

        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (!vis[i][j]) {
                    if (dfs(i, j, -1, -1, grid)) {
                        return true;
                    }
                }
            }
        }

        return false;
    }
};