export function merge(A, m, B, n) {
 let pre = 0
 let next = 0
 let result = []
 while (pre < m && next < n) {
 if (A[pre] < B[next]) {
 result.push(A[pre])
 pre++
 }
 else if (A[pre] >= B[next]) {
 result.push(B[next])
 next++
 }
 }
 // A的元素都遍历完了,B没有遍历完,next<n,将后面的元素都追加到result后面
 if (pre === m) {
 // 连接后要重新赋值
 result = result.concat(B.slice(next))
 }
 // B的元素都遍历完了
 if (next === n) {
 result = result.concat(A.slice(pre))
 }
 return result
}

merge([], 0, [1], 1)