leetcode-1. Sum of two numbers

subject ：

Given an array of integers nums  And an integer target value target, Please find... In the array And is the target value target   the   Two   Integers , And return their array subscripts .

You can assume that each input corresponds to only one answer . however , The same element in the array cannot be repeated in the answer .

You can return the answers in any order .

such as ：

Input [3,2,4],6  Then return to [1,2];（2+4 = 6）

Input [1,2,3,7,5],6  Then return to [0,4];（1+5 =6）

Their thinking

The two methods are the same , In different ways , Loop the original array twice , The current value is equal to the target value after adding the current value , You can return both subscripts

How to solve the problem

（ Two ）

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

（ One ）

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(nums, target) {
    // if(nums.length < 2)return;
   //  First set an empty array  hRes, Store results 
    let hRes = [];
   //  Loop original array 
    for(let i = 0; i< nums.length; i++){
        //  After intercepting the current cyclic value of the original array, the string gets a new array that is not cycled to  hNum
        //  Be careful   Make a deep copy of the original array and then intercept 
        let hNum = JSON.parse(JSON.stringify(nums)).splice(i+1,nums.length);
        //  Traverse the new array 
        hNum.forEach((val,index,arr) => {
            if(nums[i]+val == target){
              hRes.push(i);
              hRes.push(i+index+1);
            }
        })
    }
    // [...new Set(hRes)]  duplicate removal 
    return [...new Set(hRes)];
};

More trouble , Think the same , Put it another way , Later

Topic link ：https://leetcode.cn/problems/two-sum