LeetCode 刷题第二天

判断回文数

题目描述

Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

简要描述

判断回文数，经常做的。

实现

bool isPalindrome(int x){
    if (x < 0) return false;
    long long r = 0;long long t = x;
    int temp;

    while(x) {
        temp = x % 10;
        x /= 10;
        r = r * 10 + temp;
    }
    return r == t? true : false;
}

Runtime: 8 ms, faster than 84.26% of C online submissions for Palindrome Number.
Memory Usage: 6.9 MB, less than 97.58% of C online submissions for Palindrome Number.

取两个数组的中位数

题目描述

There are two sorted arrays nums1 and nums2 of size m and n respectively.

Find the median of the two sorted arrays. The overall run time complexity should be O(log (m+n)).

You may assume nums1 and nums2 cannot be both empty.

Example 1:

nums1 = [1, 3]
nums2 = [2]

The median is 2.0
Example 2:

nums1 = [1, 2]
nums2 = [3, 4]

The median is (2 + 3)/2 = 2.5

简要描述

把两个数组合并后，取中位数。给出的两个数组已经排序过。

思路

最简单的方法，不适用其他自定义函数，使用原生 JS 数组中内置的 sort 方法。

注意 sort方法在使用的时候一定要注意，sort 默认的是字典排序，所以在排序负数的时候，负数不是从小到大的，所以要接受一个回调函数，自定义排序方法。

实现

const findMedianSortedArrays = function(nums1, nums2) {
    const arr = [...nums1,...nums2].sort(function(a,b){return a-b;})
    if (arr.length % 2) {
        return arr[Math.floor(arr.length / 2)]
    }
    else {
        return (arr[Math.floor(arr.length / 2)] + (arr[Math.floor(arr.length / 2) - 1]) ) /2
    }
};