Leetcode 88. Merge Sorted Array

88. Merge Sorted Array

問題描述：
Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.
說白了就是陣列有序合併。

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

Example:

Input: nums1 = [1,2,3,0,0,0], m = 3 nums2 = [2,5,6], n = 3

Output: [1,2,2,3,5,6]
乍一看這題很簡單，有點需要注意的就是，下標不要越界

解法1：

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

解法2：

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