Codility – Missing Integer 문제 풀이 (난이도 : 하)

// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        
        boolean checker[] = new boolean[A.length + 1];
        
        for(int i = 0 ; i < A.length ; i++){
            int value = A[i];
            if(value > 0 && value < checker.length){
                checker[value] = true;
            }
        }
        
        for(int i = 1 ; i < checker.length ; i++){
            if(checker[i] == false){
                return i;   
            }
        }
        
        return checker.length;
    }
}