[Leetcode 781]森林中的兔子 Rabbits in Forest 巧妙

【题目】

问每只兔子，有多少只和你颜色相同的（颜色问全了，不一定问道每只兔子），求这片森林中至少有多少只兔子

There is a forest with an unknown number of rabbits. We asked n rabbits "How many rabbits have the same color as you?" and collected the answers in an integer array answers where answers[i] is the answer of the ith rabbit.

Given the array answers, return the minimum number of rabbits that could be in the forest.

 

Example 1:

Input: answers = [1,1,2]
Output: 5
Explanation:
The two rabbits that answered "1" could both be the same color, say red.
The rabbit that answered "2" can't be red or the answers would be inconsistent.
Say the rabbit that answered "2" was blue.
Then there should be 2 other blue rabbits in the forest that didn't answer into the array.
The smallest possible number of rabbits in the forest is therefore 5: 3 that answered plus 2 that didn't.

Example 2:Input: answers = [10,10,10]

Output: 11

【思路】

想清楚规律，ABC同色，兔子A说有2只同色，兔子BC也可说有2只同色

则，当有N只兔子同色时，最多可有N+1只兔子说同一个数字

class Solution {
    public int numRabbits(int[] answers) {
        int sum=0;
        int[] tmp=new int[99999];
        for(int rab:answers){
            if(tmp[rab]>0){
                tmp[rab]--;
            }
            else{
                tmp[rab]=rab;
                sum+=rab+1;
            }
        }
        return sum;
    }
}