Leetcode(88) Merge Sorted Array

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Description

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:

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

Output: [1,2,2,3,5,6]

解法

这题就是Mergesort里的merge函数，用两个指针就好啦，注意为空的判断和数组完结的处理

具体代码如下：

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class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        if (n == 0) {
            return;
        }
        int[] res = new int[m + n];
        int i = 0;
        int j = 0;
        int k = 0;
        for (; k < m + n; k++) {
            if (i == m) {
                break;
            }
            if (j == n) {
                break;
            }
            if (nums1[i] < nums2[j]) {
                res[k] = nums1[i++];
            } else {
                res[k] = nums2[j++];
            }
        }
        if (i == m) {
            while (j < n) {
                res[k++] = nums2[j++];
            }
        }
        if (j == n) {
            while (i < m) {
                res[k++] = nums1[i++];
            }
        }
        for (k = 0; k < m + n; k++) {
            nums1[k] = res[k];
        }
    }
}