【算法题】斜着打印矩阵

//      [1, 2, 3]
//     [4, 5, 6]
//     [7, 8, 9]
//     [10,11,12]
//
// print order 1, 2, 4, 3, 5, 7, 6, 8, 10, 9, 11, 12

function test() {
    let arr = [
        [1, 2, 3],
        [4, 5, 6],
        [7, 8, 9],
        [10, 11, 12]];
    let sum = arr.length + arr[0].length - 2;
    let j0 = 0, i,j
    for(let index = 0; index <= sum; index ++) {
        if(j0 === arr[0].length) {
            j0 --
        }
        j = j0
        i = index - j0
        while(j >= 0 && i <= index && i < arr.length && j < arr[0].length) {
            console.log(arr[i][j]);
            i ++;
            j = index - i;
        }
        j0 ++
    }

}

test()