LeetCode_Merge Sorted Array

Given two sorted integer arrays A and B, merge B into A as one sorted array.

Note:
You may assume that A has enough space to hold additional elements from B. The number of elements initialized in A and B are m and n respectively.

　　

class Solution {
public:
    void merge(int A[], int m, int B[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int i , j ,temp ;
        if(n== 0) return ;
        if(m== 0){
            for(i = 0; i < n; i++)
               A[i] = B[i];
          
            return ;
        }
        
      
        for(j = 0 ;j< n ;j++)
        {
              temp = B[j];
              for(i = m-1+j;  i>=0; i--)
              { 
                if(A[i]<= temp)
                   break;
                else
                  A[i+1] = A[i];
              }
              A[i+1] = temp ; 
        }
    }
};

 从后往前处理，寻找大数据插到A的后面，时间复杂度O(m+n)

class Solution {
public:
    void merge(int A[], int m, int B[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
       int cur = m + n -1;
       int lastA = m-1;
       int lastB = n-1;
       
       while(lastA>= 0 &&lastB >= 0)
       {
         A[cur--] = A[lastA] > B[lastB] ? A[lastA--]: B[lastB--];
       }
       
       while(lastB >= 0)
       {
        A[cur--] = B[lastB--] ;
       }
    }
};