[leetcode][array][two pointers] Merge Sorted Array

题目：

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

Note:

You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2. The number of elements initialized in nums1and nums2 are m and n respectively.

class Solution {
public:
//从后往前选两个数组中当前元素的较大者放入新数组
void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
if (0 == n) return;
if (0 == m){
nums1.assign(nums2.begin(), nums2.begin() + n);
return;
}
int i = m + n - 1;//i指向新数组下一个存放元素的位置
int i1 = m - 1;//i1指向nums1的当前元素
int i2 = n - 1;//i2指向nums2的当前元素
while (i1 >= 0 && i2 >= 0){
if (nums1[i1] > nums2[i2]) nums1[i--] = nums1[i1--];
else nums1[i--] = nums2[i2--];
}
while (i2 >= 0) nums1[i--] = nums2[i2--];//放入剩余的nums2中的元素
return;
}
};