Merge Sorted Array

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.

Idea: Simply do it in reverse order

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 = m - 1, j = n - 1, k = m + n - 1;
        while (i >= 0 && j >= 0) {
            if (A[i] < B[j]) {
                A[k] = B[j];
                --j;
            }
            else {
                A[k] = A[i];
                --i;
            }
            --k;
        }
        
        while (j >= 0) {
            // copy the rest of B into A
            A[k] = B[j];
            --k;
            --j;
        }
    }
};