public int getMax(String[][] str){ int r = str.length,c = str[0].length; int dp[][] = new int[r][c]; if(str[0][0] == "X") return -1; dp[0][0] = 1; if(str[1][0] == ".") dp[1][0] = 1; for(int j = 1;j<c;j++){ for(int i = 0;i<2;i++){ if(str[i][j] == "."){ dp[i][j] += str[i^1][j] == "."?dp[i^1][j-1]:0; dp[i][j] += dp[i][j-1]; }else{ dp[i][j] = 0; } } } return dp[1][c-1] == 0?-1:dp[1][c-1]; }