少了一个；
package com.code;
import java.util.Arrays;
public class Test03_2 {
public static int solution(int[] A) {
// write your code in Java SE 8
Arrays.sort(A);
int size = A.length;
if(size==0){
return 1;
}
if(size==1){
return A[0]==1?2:1;
}
if(A[size-1]==size){
return size+1;
}
for (int i=0;i<size;i++){
if(A[i]> i+1){
return (i+1);
}
}
return -1;
}
public static void main(String[] args) {
int [] a = {1,2,3,4};
System.out.println( solution(a));
int [] b = {2,3,4,5};
System.out.println(solution(b));
int [] c = {};
System.out.println(solution(c));
int [] d = {1};
System.out.println(solution(d));
}
}
/**
A zero-indexed array A consisting of N different integers is given.
The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing.
Your goal is to find that missing element.
Write a function:
class Solution { public int solution(int[] A); }
that, given a zero-indexed array A, returns the value of the missing element.
For example, given array A such that:
A[0] = 2
A[1] = 3
A[2] = 1
A[3] = 5
the function should return 4, as it is the missing element.
Assume that:
N is an integer within the range [0..100,000];
the elements of A are all distinct;
each element of array A is an integer within the range [1..(N + 1)].
Complexity:
expected worst-case time complexity is O(N);
expected worst-case space complexity is O(1), beyond input storage (not counting the storage required for input arguments).
Elements of input arrays can be modified.
*/