function findSmallestMissingNumber(arr) {
let min = arr[0];
const len = arr.length;
for (let i = 1; i < len; i++) {
if (arr[i] > min + 1) {
return min + 1;
} else {
min = arr[i];
}
}
return -1;
}
const arr = [18, 19, 20, 21, 22, 29, 33, 36, 40, 42];
console.log(findSmallestMissingNumber(arr));
/*
run:
23
*/