Javascipt version

Javascript have the function that reverse the String, so it is pretty easy to do in js.

/**
 * @param {number} x
 * @return {number}
 */
var reverse = function(x) {
    var y = parseInt(x.toString().split('').reverse().join(''))
    if (y >= 2**31-1 || -y <= -(2**31)) return 0;
    return x < 0 ?  -y : y
}

Java version

This java version is not prefect through, I have not handle the overflow.

public class Solution {
    public static int reverse(int x) {
        int result = 0;
        if(x == 10){return 1;}
        while (x!=0){
            int tail = x % 10;
            int newResult = result * 10 + tail;
            result =newResult;
            x = x /10;
        }
        return result;
    }
    public static void main(String[] args){
        System.out.print(reverse(123));
    }
}

Posted 2021-08-06Updated 2023-05-07leetcodea few seconds read (About 60 words)

leetcode two-sum javascript

Version 1:

A simple nested for loop

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    for (let i = 0;i<nums.length ;i++){
        let tmp = target - nums[i]
        for (let j = i+1;j<nums.length;j++){
            if(tmp === nums[j]){
                return [i,j]
            }
        }
    }
};

Version 2:

HashMap have much better search time than a normal queue loop

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    const map = new Map()
    
    for (let i = 0; i< nums.length;i++){
        const num = nums[i]
        const difference = target - num
        
        if (map.has(num)){
            return [map.get(num), i]
        }
        
        map.set(difference, i)
    }
};

Version 2.5 Java

public class Solution {
    public static int[] twoSum(int[] nums, int target) {
        Map<Integer , Integer> map = new HashMap<Integer,Integer>();
        for(int i = 0 ; i < nums.length ; i++) {
            int targetTemp = target - nums[i];
            if(map.containsKey(targetTemp)) {
                return new int[] { map.get(targetTemp) , i};
            }
            map.put(nums[i], i);
        }
    throw new IllegalArgumentException("No solution");
    }
}

leetcode Reverse Integer

Javascipt version

Java version

leetcode two-sum javascript

Version 1:

Version 2:

Version 2.5 Java

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