java - 寻找缺失的整数(Codility 测试)

Question

我在 Codility 上发现这个练习时遇到了一个非常奇怪的问题，这是任务描述:

Write a function:

class Solution { public int solution(int[] A); }  

that, given a non-empty zero-indexed array A of N integers, returns the minimal positive integer that does not occur in A.

For example, given:

    A[0] = 1
    A[1] = 3
    A[2] = 6
    A[3] = 4
    A[4] = 1
    A[5] = 2

the function should return 5.

Assume that:
N is an integer within the range [1..100,000];
each element of array A is an integer within the range [−2,147,483,648..2,147,483,647].

Complexity:
expected worst-case time complexity is O(N);
expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments).
Elements of input arrays can be modified.

还有我的代码:

class Solution {
    public int solution(int[] A) {
        SortedSet set = new TreeSet();
        for (int i = 0; i < A.length; i++)
            if (A[i] > 0)
                set.add(A[i]);
        Iterator it = set.iterator();
        int previous = 0, element = 0;
        try { previous = (int)it.next(); }
        catch (NoSuchElementException e) { return 1; }
        while (it.hasNext()) {
            element = (int)it.next();
            if (element!=(previous+1)) break;
            previous=element;
        }
        if (previous+1 < 1) return 1;
        return previous+1;
    }
}

代码分析:

http://i.stack.imgur.com/IlMxP.png

我想弄清楚为什么我的代码只在那个测试中提供了错误的输出，有人能帮助我吗？

提前致谢!

Answer 1

我的解决方案得分为 100/100

// 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");
import java.util.Arrays;

class Solution {

    public int solution(int[] A) {

        int smallest = 1;

        Arrays.sort(A);
        for (int i = 0; i < A.length; i++) {

            if (A[i] == smallest) {

                smallest++;
            }
        }

        return smallest;
    }
}

“large_2”测试用例的时间更差，为 0.292 秒。

我会说非常好。

如果您需要解释，请联系我，以便我扩展答案:)

干杯。