88. Merge Sorted Array

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 nums1 and nums2 are m and n respectively.

class Solution {public:    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {        int a=m+n-1;        int i=m-1;        int j=n-1;        while(i>=0&&j>=0)        {          if(nums1[i]>nums2[j])             nums1[a--] =nums1[i--];          else             nums1[a--] =nums2[j--];        }        while(j>=0)        {            nums1[a--]=nums2[j--];        }    }};

思想：从后往前比较，对应nums1而言，一个地方是vector最后面，一个是vector中不为0的最后一个数。用nums1中不为0的数与nums2比较。然后往前加。