矩阵中的路径

public class Solution {
    public boolean hasPath(char[] matrix, int rows, int cols, char[] str)
    {
        boolean[] flag=new boolean[matrix.length]; // flag数组默认初始化为falsefor(int i =0;i < rows;i ++){
            for(int j=0;j < cols; j ++){
                if(judge(matrix,flag,rows,cols,i,j,str,0)){
                    return true;
                }
            }
        }
        return false;
    }

    private boolean judge(char[] matrix,boolean[] flag, int rows, int cols, int i, int j, char[] str, int k) {
        int index=cols*i + j;
        if(i <0 ||j<0||i >= rows || j >= cols || matrix[index] != str[k] || flag[index] == true){
            return false;
        }
        if(k == str.length-1)
            return true;
        flag[index] = true;
        if(judge(matrix,flag,rows,cols,i-1,j,str,k+1)||
                judge(matrix,flag,rows,cols,i+1,j,str,k+1) ||
                judge(matrix,flag,rows,cols,i,j-1,str,k+1) ||
                judge(matrix,flag,rows,cols,i,j+1,str,k+1)){
            return true;
        }
        flag[index] = false;
        return false;
    }
}