88 Merge Sorted Array

链接：https://leetcode.com/problems/merge-sorted-array/
问题描述：
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.

Hide Tags Array Two Pointers
Hide Similar Problems (E) Merge Two Sorted Lists

归并两个数组，要注意的是输入中m和n两个数字指定了两个数组中的前m个数字和n个数字有效。这一题也可以用二分法排序。

class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        while(nums1.size()>m)
            nums1.pop_back();
        while(nums2.size()>n)
            nums2.pop_back();

        nums1.insert(nums1.begin(),nums2.begin(),nums2.end());
        sort(nums1.begin(),nums1.end());
    }
};

也可以用归并排序。

class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        while(nums1.size()>m)
            nums1.pop_back();
        while(nums2.size()>n)
            nums2.pop_back();


        vector<int>::iterator it1=nums1.begin();
        vector<int>::iterator it2=nums2.begin();
        while(it1!=nums1.end()&&it2!=nums2.end())
          if(*it1>=*it2)
              nums1.insert(it1,*it2++); 
          else
              it1++;

        while(it2!=nums2.end())
            nums1.push_back(*it2++);
    }
};