SOURCE

console.log(666)
function merge( A, m, B, n ) {
    let p = m + n - 1
    let pA = m - 1
    let pB = n - 1
    while(pA >=0 && pB >=0){
        if(A[pA] >= B[pB]){
            A[p--] = A[pA--]
        }else{
            A[p--] = B[pB--]
        }
    }
    while(pB >=0 ){
        A[p--] = B[pB--]
    }
    return A
}

function mergeList(arrs){
    //  分为两半，然后对这两半进行mergeList，变为两个数组，最后调用merge函数
    if(arrs.length === 0) return []
    if(arrs.length === 1) return arrs[0].sort((a, b) => a - b)

    const len = arrs.length
    const mid = Math.ceil(len / 2)
    const left = arrs.slice(0, mid)
    const right = arrs.slice(mid, len)
    const newA = mergeList(left)
    const newB = mergeList(right)
    return merge(newA.concat(new Array(newB.length).fill(0)), newA.length, newB, newB.length)

}

console.log((mergeList([
    [1,2,3],
    [2,5,6],
    [9,7,5]
])))