2020 BIT冬训-贪心 G - Voting CodeForces - 749C

标签：turn   not   rac   ons   red   procedure   font   imp   moment   

Problem Description

There are n employees in Alternative Cake Manufacturing (ACM). They are now voting on some very important question and the leading world media are trying to predict the outcome of the vote.

Each of the employees belongs to one of two fractions: depublicans or remocrats, and these two fractions have opposite opinions on what should be the outcome of the vote. The voting procedure is rather complicated:

1. Each of n employees makes a statement. They make statements one by one starting from employees 1 and finishing with employee n. If at the moment when it‘s time for the i-th employee to make a statement he no longer has the right to vote, he just skips his turn (and no longer takes part in this voting).
2. When employee makes a statement, he can do nothing or declare that one of the other employees no longer has a right to vote. It‘s allowed to deny from voting people who already made the statement or people who are only waiting to do so. If someone is denied from voting he no longer participates in the voting till the very end.
3. When all employees are done with their statements, the procedure repeats: again, each employees starting from 1 and finishing with n who are still eligible to vote make their statements.
4. The process repeats until there is only one employee eligible to vote remaining and he determines the outcome of the whole voting. Of course, he votes for the decision suitable for his fraction.

You know the order employees are going to vote and that they behave optimal (and they also know the order and who belongs to which fraction). Predict the outcome of the vote.

Input

The first line of the input contains a single integer n (1?≤?n?≤?200?000) — the number of employees.

The next line contains n characters. The i-th character is ‘D‘ if the i-th employee is from depublicans fraction or ‘R‘ if he is from remocrats.

Output

Print ‘D‘ if the outcome of the vote will be suitable for depublicans and ‘R‘ if remocrats will win.

Examples

5
DDRRR

D

6
DDRRRR

R

Note

Consider one of the voting scenarios for the first sample:

1. Employee 1 denies employee 5 to vote.
2. Employee 2 denies employee 3 to vote.
3. Employee 3 has no right to vote and skips his turn (he was denied by employee 2).
4. Employee 4 denies employee 2 to vote.
5. Employee 5 has no right to vote and skips his turn (he was denied by employee 1).
6. Employee 1 denies employee 4.
7. Only employee 1 now has the right to vote so the voting ends with the victory of depublicans.

这题的思路用使用队列模拟。

用两个队列来维护。一个表示D,一个表示R.

分别存入他们所在的位置后，比较两个队列首的元素。将较小的那一个+n后放入该队列的尾部（+n代表下一轮循环）。

然后再同时将队首元素pop。直到有一个队列为空。不为空的那个队列所表示是的就是答案。

AC代码如下

#include<cstdio>
#include<algorithm>
#include<queue>
using namespace std;
char v[200005];
int n;
queue<int>r,d;
int main(){
    scanf("%d%s",&n,v);
    for(int i=0;i<n;i++){
        if(v[i]==‘R‘)
            r.push(i);
        else
            d.push(i);
    }
    while(!r.empty()&&!d.empty()){
        if(r.front()<d.front())
            r.push(r.front()+n);
        else
            d.push(d.front()+n);
        d.pop();
        r.pop();    
    }
    if(r.empty())
        printf("D");
    else
        printf("R");
    return 0;
}

2020 BIT冬训-贪心 G - Voting CodeForces - 749C

标签：turn   not   rac   ons   red   procedure   font   imp   moment   

原文地址：https://www.cnblogs.com/mikku39/p/14393828.html