2 - Sum of Three Values

Problem Statement

Given an array of integers, nums, and an integer value, target, determine if there are any three integers in nums whose sum equals the target. Return TRUE if three such integers are found in the array. Otherwise, return FALSE.

Example 1:

Input: nums = [1,-1,0], target = -1
Output: false

Example 2:

Input: nums = [3,7,1,2,8,4,5], target = 10
Output: True

Constraints:

• 3 <= nums.length <= 1000
• -10³ <= nums[i] <= 10³
• -10³ <= target <= 10³

Approach 1: Two Pointer Approch

Python

Written by @kondekarshubham123

def find_sum_of_three(nums, target):
    nums.sort()
    for i in range(len(nums) - 2):
        new_target = target - nums[i]
        left = i + 1
        right = len(nums) - 1

        while left < right:
            new_sum = nums[left] + nums[right]
            if new_sum == new_target:
                return True
            
            if new_sum > new_target:
                right -= 1
            else:
                left += 1

    return False

Java

Written by @kondekarshubham123

import java.util.*;


public class SumOfThree{
   public static boolean findSumOfThree(int[] nums, int target) {
      Arrays.sort(nums);
      
      int numsSize = nums.length;

      for(int ptr1 = 0; ptr1 < numsSize - 2 ; ptr1 ++){
         int ptr2 = ptr1 + 1;
         int ptr3 = numsSize - 1;

         int newTarget = target - nums[ptr1];

         while(ptr2 < ptr3){
            int new_sum = nums[ptr2] + nums[ptr3];

            if(newTarget == new_sum){
               return true;
            } else if (new_sum > newTarget){
               ptr3 -= 1;
            } else {
               ptr2 += 1;
            }
         }
      }
      return false;
   }
}