可以用双指针思想,两个数组比较当前元素大小,小的先拿进新建立起的数组

import java.util.*;
public class Solution {
    public void merge(int A[], int m, int B[], int n) {
        int[] result = new int[m+n];
        int i = 0,j = 0,p = 0;
        int flag = 0;
        while(i<m||j<n){
            if(i == m){
                flag = B[j];
                j++;
            }
            else if(j == n){
                flag = A[i];
                i++;
            }
            else if(A[i]<B[j]){
                flag = A[i];
                i++;
            }
            else{
                flag = B[j];
                j++;
            }
            result[p++] = flag;
        }
        for(int k = 0;k < result.length;k++){
            A[k] = result[k];
        }
        
    }
}