88. Merge Sorted Array

• Difficulty: Easy

• Topics: Array, Two Pointers

• Similar Questions:

  • Merge Two Sorted Lists

  • Squares of a Sorted Array

  • Interval List Intersections

Problem:

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array.

Note:

• The number of elements initialized in nums1 and nums2 are m and n respectively.
• You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold additional elements from nums2.

Example:

Input:
nums1 = [1,2,3,0,0,0], m = 3
nums2 = [2,5,6],       n = 3

Output: [1,2,2,3,5,6]

Solutions:

class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        nums1.resize(m + n);
        int cur = m + n - 1;
        int i1 = m - 1;
        int i2 = n - 1;

        while (i1 >= 0 || i2 >= 0) {
            if (i1 < 0) {
                nums1[cur--] = nums2[i2--];
            } else if (i2 < 0) {
                break;
            } else {
                if (nums1[i1] >= nums2[i2]) {
                    nums1[cur--] = nums1[i1--];
                } else {
                    nums1[cur--] = nums2[i2--];
                }
            }
        }
    }
};