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three sum algorithm

Mysterious Macaque answered on July 26, 2022 Popularity 9/10 Helpfulness 3/10

answer three sum algorithm

three sum algorithm

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const nums = [-5, -5, -4, -4, -4, -2, -2, -2, 0, 0, 0, 1, 1, 3, 4, 4]    // already sorted

// Time complexity: O(n^2)
// Space Complexity: O(1)
const threeSum = function(nums) {
    let output = []

    nums.sort((a, b) => { return a - b })

    for (let i = 0; i < nums.length - 2; i++) {
        if (i > 0 && nums[i] === nums[i - 1]) {
            continue
        }

        let l = i + 1
        let r = nums.length - 1

        while (l < r) {
            let sum = nums[i] + nums[l] + nums[r]

            if (sum < 0) {
                l++
            }

            if (sum > 0) {
                r--
            }

            if (sum === 0) {
                output.push([nums[i], nums[l], nums[r]])
                l++
                r--

                while (nums[l] === nums[l - 1] && l < r) {
                    l++
                }
                while (nums[r] === nums[r + 1] && l < r) {
                    r--
                }
            }
        }
    }

    return output
}

console.log(threeSum(nums))
// [Log]:
[
  [ -5, 1, 4 ],
  [ -4, 0, 4 ],
  [ -4, 1, 3 ],
  [ -2, -2, 4 ],
  [ -2, 1, 1 ],
  [ 0, 0, 0 ]
]

Popularity 9/10 Helpfulness 3/10 Language javascript

Source: Grepper

Tags: algorithm javascript sum

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Contributed on Jul 26 2022

Mysterious Macaque

0 Answers Avg Quality 2/10

three sum algorithm

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