// Given an array of integers, 
//write a JavaScript function that finds and prints 
//all pairs of numbers in the array that sum up to 17. 
//Optimize the function to have a time complexity of O(n).
const newArr = [1,2,13,4,15,18,-1]

const checkPairs = (arr, sum) => {
    const seen = {}
    for(value of arr){
        const currentNumber = value
        const toCheckFromStoredNo = sum - currentNumber
        if(seen[toCheckFromStoredNo]){
            console.log("pairs are", toCheckFromStoredNo, currentNumber)
        }
        seen[currentNumber] = true
        
    }
}

checkPairs(newArr, 17)