codility-solution4.js

/*
find smallest positive integer not in array
*/
function solution(A) {
    // write your code in JavaScript (Node.js 8.9.4)
	var len = A.length;
	if(len===0)	return 1;
	
	if(len===1){
		if(A[0]===1)	return 2;
		else			return 1;
	}
	var arr = [];
	var isSorted = 1;
	for(var i=0; i< len; i++){
		if(A[i]>0)	arr[A[i]] = true;
		if(A[i]===isSorted){
			isSorted++;
		}
	}
	if(isSorted === len+1) return isSorted;
	if(arr.length===0)	return 1;
	if(arr.length===1){
		if(A[0]>1)	return 1;
		else		return 2;
	}
	
	for(var i=1; i <= arr.length; i++){
		if(arr[i] === undefined){
			return i;
		}
	}
}