Run results for: two sum - MeasureThat.net

Test name	Executions per second
✓ brute force	57,758,608 Ops/sec
memo	49,313,092 Ops/sec
hash	143,626 Ops/sec

brute force

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]
        }
    }
    return [];
};
twoSum([2,7,11,15], 9)

memo

var twoSum = function(nums, target) {
  let sol = [];
    for(let i=0; i<nums.length; i++) {
      if(sol.length) break;
      for(let j=i+1; j<nums.length; j++) {
        if(sol.length) break;
        if(nums[i]+nums[j]===target) sol = [i,j]
      }
    }
    return sol;
}
twoSum([2,7,11,15], 9)

hash

var twoSumHash = function (nums, target)
{
  let hashTable = []
  let pair = []
  let i = 0;
  let foundPair = false
  while (i < nums.length) {
    hashTable[nums[i]] = i
    i += 1
  }
  i = 0
  while (i < nums.length && !foundPair)  {
    let compliment = target - nums [i]
    if (compliment in hashTable) {
      if (i !== hashTable[compliment]) {
        pair.push(i)
        pair.push(hashTable [compliment])
        foundPair = true
      }
    }
    i += 1
  }

  return pair
}

console.log(twoSumHash([2,7,11,15], 9))