function largestOfFour(arr) {
    //二维数组中寻找各元素中最大值算法
    var max = [];
    for(var i = 0; i < arr.length; i++){
        max.push(0);
        for(var j = 0; j < arr[i].length; j++){
            if(arr[i][j] > max[i]){
                max[i] = arr[i][j];
            }
        }
    }
    return max;
}


largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);