Title Description

Please design a function to determine whether there is a path containing all characters of a string in a matrix. The path can start from any lattice in the matrix, and each step can move one lattice left, right, up and down in the matrix. If a path passes through a lattice in the matrix, it cannot enter the lattice again. For example, a 3 X 4 matrix such a s a b c e s f c s a d e e contains a path of the string "bcced", but the matrix does not contain a path of "abcb", because the path cannot enter the lattice again after the first character B of the string occupies the second lattice in the first row of the matrix.

link

https://www.nowcoder.com/practice/c61c6999eecb4b8f88a98f66b273a3cc?tpId=13&tqId=11218&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

Code

class Solution {
public:
    bool hasPath(char* matrix, int rows, int cols, char* str)
    {
        bool flag = false;
        int **visited = (int**)malloc(sizeof(int*) * rows);
        for(int i = 0; i < rows; i++){
            visited[i] = (int*)malloc(sizeof(int) * cols);
        }
        for(int i = 0; i < rows; i++){
            for(int j = 0; j < cols; j++){
                for(int k = 0; k < rows; k++){
                    for(int t = 0; t < cols; t++){
                        visited[k][t] = 0;
                    }
                }
                flag = flag || path(matrix, visited, rows, cols, i, j, str);
            }
        }
        return flag;
    }
    bool path(char* matrix, int** visited, int rows, int cols, int i, int j, char *str){
        bool flag = false;
        if(matrix[i*cols+j] != str[0]){
            return false;
        }
        else{
            visited[i][j] = 1;
            if(str[1] == '\0'){
                return true;
            }
            if(i - 1 >= 0 && visited[i-1][j] == 0){  // You can go up
                flag = flag || path(matrix, visited, rows, cols, i-1, j, str+1);
            }
            if(i + 1 <= rows-1 && visited[i+1][j] == 0){ // You can go down
                flag = flag || path(matrix, visited, rows, cols, i+1, j, str+1);
            }
            if(j - 1 >= 0 && visited[i][j-1] == 0){ // You can still go left
                flag = flag || path(matrix, visited, rows, cols, i, j-1, str+1);
            }
            if(j + 1 <= cols-1 && visited[i][j+1] == 0){ // You can also go right
                flag = flag || path(matrix, visited, rows, cols, i, j+1, str+1);
            }
            return flag;
        }
    }
};