hasPairWithSum (Google Question)
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// Naive
function hasPairWithSum(arr, sum){
var len = arr.length;
for(var i =0; i<len-1; i++){
for(var j = i+1;j<len; j++){
if (arr[i] + arr[j] === sum)
return true;
}
}
return false;
}
// Better
function hasPairWithSum2(arr, sum){
const mySet = new Set();
const len = arr.length;
for (let i = 0; i < len; i++){
if (mySet.has(arr[i])) {
return true;
}
mySet.add(sum - arr[i]);
}
return false;
}
hasPairWithSum2([6,4,3,2,1,7], 9)
JavaScript
INFO