sumZero.js

//Multiple Pointers - Problem solving pattern

//Naive Solution with Time complexity - O(N^2) & Space complexity - O(1)
// function sumZero(arr){
//     for(let i = 0; i < arr.length; i++){
//         for(let j = i + 1; j < arr.length; j++){
//             if(arr[i] + arr[j] === 0){
//                 return [arr[i],arr[j]];
//             }
//         }
//     }
// }

//Time complexity - O(N) & Space complexity - O(1)
function sumZero(arr) {
    let left = 0;
    let right = arr.length -1;
    while(left < right){
        let sum = arr[left] + arr[right];
        if(sum === 0){
            return [arr[left],arr[right]];
        } else if(sum > 0){
            right--;
        } else {
            left++;
        }
    }
}


sumZero([-3,-2,-1,0,1,2]) //returns [-2,2]