88. Merge Sorted Array

88. 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 nums1 and nums2 are m and n respectively.

解析

• 最优解：从后往前处理,不需要开辟额外空间

class Solution_88 {
public:
	// merge nums2 into nums1 as one sorted array.
	void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {

		if (m==0)
		{
			for (int i = 0; i < n;i++)
			{
				nums1.push_back(nums2[i]);
			}
			return;
		}
		if (n==0)
		{
			return;
		}
		int len1 = m - 1;
		int len2 = n - 1;
		int index = m + n - 1;
		while (len1>=0&&len2>=0)
		{
			if (nums2[len2]>nums1[len1])
			{
				nums1[index--] = nums2[len2--];
			}
			else
			{
				nums1[index--] = nums1[len1--];
			}
		}

		while (len2>=0)
		{
			nums1[index--] = nums2[len2--];
		}

		return;
	}

	void merge(int A[], int m, int B[], int n) {
		int i = m - 1;
		int j = n - 1;
		int index = m + n - 1;

		while (i>=0&&j>=0)
		{
			A[index--] = (A[i] > B[j]) ? A[i--] : B[j--];
		}
		while (j>=0)
		{
			A[index--] = B[j--];
		}
		return;
	}
};

题目来源

• 88. Merge Sorted Array