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65

Javascript twoSum algorithm: Given an array of integers, return indices of the two numbers such that they add up to a specific target

rated 0 times [ 71] [ 6] / answers: 1 / hits: 65298 / 5 Years ago, sun, august 18, 2019, 12:00:00

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

Example:

Given nums = [3, 2, 4], target = 6,

Because nums[1] + nums[2] = 2 + 4 = 6

return [1, 2].

Solution

var twoSum = function(nums, target) {

    for(let i = 0; i <= nums.length; i++){

        for(let j = 0; j <= nums.length; j++){

            if(nums[i] + nums[j] == target){

                return [i, j]

            }

        }

    }

};

The code above works in other cases but not this one.

Expected result [1,2]

Output [0,0]

For instance, I've tried to use a different array of numbers and a different target and it works even if you change the order of the numbers

Example:

New array: [15, 7, 11, 2], target = 9,

Output: [1, 3].

I don't understand what is wrong with the solution and I hope that someone can explain. Thanks

Answers

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eden

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2 Years ago

answered 5 Years ago arthur · Accepted Answer

I don't understand what is wrong with the solution and I hope that
someone can explain ?

Here you're both inner and outer loop start from 0^th so in the case [3,2,4] and target 6 it will return [0,0] as 3 + 3 is equal to target, so to take care of same index element not being used twice created a difference of 1 between outer and inner loop

Make outer loop to start from 0^th index and inner loop with value i+1

var twoSum = function(nums, target) {

    for(let i = 0; i < nums.length; i++){

        for(let j = i+1; j < nums.length; j++){

            if(nums[i] + nums[j] == target){

                return [i, j]

            }

        }

    }

};



console.log(twoSum([15, 7, 11, 2],9))

console.log(twoSum([3, 2, 4],6))