缺失数字

 

 

package my;

import java.util.Arrays;

public class MissNumberSolution {
    public int missingNumber(int[] nums) {
            Arrays.sort(nums);
            if (nums[nums.length-1] != nums.length) {
                return nums.length;
            }
            if(nums[0] != 0 ){
                return 0;
            }

            for(int i = 1 ; i< nums.length;i++){
                int missNumber = nums[i-1] + 1;
                if(nums[i] != missNumber){
                    return missNumber;
                }
            }
            return -1 ;
    }
    public static void main(String[] args){
        int[] nums ={0,1,3,4,2,5,7};
        int  m = new MissNumberSolution().missingNumber(nums);
        System.out.println(m);
    }
}