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 nums1and nums2 are m and n respectively.

Approach : Push the nums1 elements in the end first since no extra space is to be used. Next, use the merge sort merge routine to merge the two sorted arrays. 

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