Posted Updated LeetCode / Easya few seconds read (About 106 words)

283. Move Zeroes

问题描述
Given an integer array nums, move all 0’s to the end of it while maintaining the relative order of the non-zero elements.

Note that you must do this in-place without making a copy of the array.

双指针，i指针左侧保留大于零的元素，j指针左侧保留等于零的元素。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
class Solution {
    public void moveZeroes(int[] nums) {
        int i = 0;
        int j = 0;
        while ( j < nums.length ){
            if ( nums[j] != 0 ){
                int temp = nums[i];
                nums[i] = nums[j];
                nums[j] = temp;
                
                i++;
            }
            j++;
        }
    }
}

Posted Updated LeetCode / Easya minute read (About 187 words)

88. Merge Sorted Array

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

采用双指针，从结尾开始遍历两个数组。
比较后按倒叙插入第一个数组。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
class Solution {
    public void merge(int[] nums1, int m, int[] nums2, int n) {
        int i = m - 1 , j = n - 1, k = m + n - 1;
        
        while ( i >= 0 && j >= 0 ) {
            if ( nums1[i] < nums2[j] ){
                nums1[k] = nums2[j];
                j--;
                k--;
            }               
            else {
                nums1[k] = nums1[i];
                i--;
                k--;
            }
        }
        if ( i < 0 ){
            while ( j >= 0 ){
                nums1[k] = nums2[j];
                j--;
                k--;
            }
        }
    }
}

Posted Updated LeetCode / Easya minute read (About 118 words)

977. Squares of a Sorted Array

Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number sorted in non-decreasing order.

采取双指针，同时比较两侧的正负及大小。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
class Solution {
    public int[] sortedSquares(int[] nums) {
        int left = 0;
        int right = nums.length - 1;
        int i = nums.length-1;
        int[] ans = new int[nums.length];
        
        while (left <= right) {
            if ( nums[left] < 0 ){
                if ( (-nums[left]) < nums[right] ){
                    ans[i] = nums[right] * nums[right];
                    right--;
                }
                else {
                    ans[i] = nums[left] * nums[left];
                    left++;
                }
                i--;
            }
            else{
                if ( nums[left] < nums[right] ){
                    ans[i] = nums[right] * nums[right];
                    right--;
                }
                else{
                    ans[i] = nums[left] * nums[left];
                    left++;
                }
                i--;
            }
        }
        return ans;
    }
}

Follow

Recents

Archives

Links

×