[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 (size that is greater or equal to m + n) to hold additional elements from B. The number of elements initialized in A and B are m andn respectively.

 

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 Array Two Pointers

 

 

思路 ： A前面的数据有用，但是超过n之后的数据没有，可以从后向前比较，结果写入A[m+n-1]中即可。

class Solution {
    public:
        void merge(int A[], int m, int B[], int n)
        {   
            int index = m + n - 1;
            m--;
            n--;

            while(m >= 0 && n >= 0)
            {   
                if(A[m] > B[n])
                {   
                    A[index] = A[m];
                    m--;
                }   
                else
                {   
                    A[index] = B[n];
                    n--;
                }   
                index--;
            }   
            while(n >= 0)
            {   
                A[index] = B[n];
                n--;
                index--;
            }   

        }   
};