CF651A Joysticks

最新推荐文章于 2022-01-12 19:23:36 发布

ShadyPi

最新推荐文章于 2022-01-12 19:23:36 发布

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分类专栏： # 贪心

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本文介绍了一个关于两个游戏控制器充电的问题，通过贪心算法确定游戏能持续的最大时间。输入包括两个控制器的初始电量，输出则是游戏可以持续的最长时间。

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原题链接：http://codeforces.com/problemset/problem/651/A

Joysticks

Description

Friends are going to play console. They have two joysticks and only one charger for them. Initially first joystick is charged at a1 percent and second one is charged at a2 percent. You can connect charger to a joystick only at the beginning of each minute. In one minute joystick either discharges by 2 percent (if not connected to a charger) or charges by 1 percent (if connected to a charger).

Game continues while both joysticks have a positive charge. Hence, if at the beginning of minute some joystick is charged by 1 percent, it has to be connected to a charger, otherwise the game stops. If some joystick completely discharges (its charge turns to 0), the game also stops.

Determine the maximum number of minutes that game can last. It is prohibited to pause the game, i. e. at each moment both joysticks should be enabled. It is allowed for joystick to be charged by more than 100 percent.

Input

The first line of the input contains two positive integers a1 and a2 (1 ≤ a1, a2 ≤ 100), the initial charge level of first and second joystick respectively.

Output

Output the only integer, the maximum number of minutes that the game can last. Game continues until some joystick is discharged.

Examples

input

3 5

output

input

4 4

output

Note

In the first sample game lasts for 6 minute by using the following algorithm:

at the beginning of the first minute connect first joystick to the charger, by the end of this minute first joystick is at 4%, second is at 3%;
continue the game without changing charger, by the end of the second minute the first joystick is at 5%, second is at 1%;
at the beginning of the third minute connect second joystick to the charger, after this minute the first joystick is at 3%, the second one is at 2%;
continue the game without changing charger, by the end of the fourth minute first joystick is at 1%, second one is at 3%;
at the beginning of the fifth minute connect first joystick to the charger, after this minute the first joystick is at 2%, the second one is at 1%;
at the beginning of the sixth minute connect second joystick to the charger, after this minute the first joystick is at 0%, the second one is at 2%.
After that the first joystick is completely discharged and the game is stopped.

题解

巨水，贪心可做，只需要每次给电量少的充电，玩电量低的就好。

注意在电量为1的时候也不能玩。

代码

#include<bits/stdc++.h>
using namespace std;
int a,b;
void in()
{scanf("%d%d",&a,&b);}
void ac()
{
    int ans=0;
    while(a>0&&b>0)
    {
        if(max(a,b)<=1)printf("%d\n", ans),exit(0);
        if(min(a,b)==0)printf("%d\n",ans), exit(0);
        if(a>b)a-=2,b+=1;
        else a+=1,b-=2;
        ans++;
    }
    printf("%d\n",ans);
}
int main()
{
    in();ac();
    return 0;
}