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
    
     & nums1, int m, vector
     
      & 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