Codeforces Problem - 39E - What Has Dirichlet Got to Do with That?(博弈,记忆化搜索)

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E. What Has Dirichlet Got to Do with That?
time limit per test
2 seconds
memory limit per test
64 megabytes
input
standard input
output
standard output

You all know the Dirichlet principle, the point of which is that if n boxes have no less than n + 1 items, that leads to the existence of a box in which there are at least two items.

Having heard of that principle, but having not mastered the technique of logical thinking, 8 year olds Stas and Masha invented a game. There are a different boxes and b different items, and each turn a player can either add a new box or a new item. The player, after whose turn the number of ways of putting b items into a boxes becomes no less then a certain given number n, loses. All the boxes and items are considered to be different. Boxes may remain empty.

Who loses if both players play optimally and Stas's turn is first?

Input

The only input line has three integers a, b, n (1 ≤ a ≤ 100001 ≤ b ≤ 302 ≤ n ≤ 109) — the initial number of the boxes, the number of the items and the number which constrains the number of ways, respectively. Guaranteed that the initial number of ways is strictly less than n.

Output

Output "Stas" if Masha wins. Output "Masha" if Stas wins. In case of a draw, output "Missing".

Examples
input
Copy
2 2 10
output
Copy
Masha
input
Copy
5 5 16808
output
Copy
Masha
input
Copy
3 1 4
output
Copy
Stas
input
Copy
1 4 10
output
Copy
Missing
Note

In the second example the initial number of ways is equal to 3125

  • If Stas increases the number of boxes, he will lose, as Masha may increase the number of boxes once more during her turn. After that any Stas's move will lead to defeat. 
  • But if Stas increases the number of items, then any Masha's move will be losing.

题意:

给出a,b,n,每次只能使a,b其中一个数+1 ,谁使得 a^b >= n 谁就输了,输出输了的人,若平局输出Mission


平局的情况只会在a=1时出现,所以另外讨论一下。


其余就记忆化搜索得到每个状态的胜败态。


#include <iostream>
#include <string.h>
#include <stdio.h>
using namespace std;
typedef long long LL;
const int N = 1e5 ;
LL a,b,n,base[N][50];
int dp[N][50];
//dp[i][j] = 1 为先手必胜态
int dfs(LL x,LL y){
    if(dp[x][y]) return dp[x][y];
    if(base[x][y]>=n) return dp[x][y] = 1;
    if(x*x>=n){
        // 处理 b = 1 的情况, 避免数组越界
        // n<=1e9 当 x*x>=n 时只能增加x,可以知道操作的次数以及最终的结果
        if((n-x)%2==0) return dp[x][y] = 1;
        else return dp[x][y] = 2;
    }
    if(dfs(x+1,y)==2||dfs(x,y+1)==2){
        return dp[x][y] = 1;
    }
    return dp[x][y] = 2;
}
int main()
{
    scanf("%lld%lld%lld",&a,&b,&n);
    for(int i=1;i<N;i++){
        base[i][0] = 1;
        for(int j=1;j<=40;j++){
            base[i][j] = base[i][j-1]*i;
            if(base[i][j]>=n){
                for(int k=j;k<=40;k++) base[i][k] = n;
                break;
            }
        }
    }
    dfs(a,b);//先得到所有的结果
    if(a==1){
        int i;
        for(i = 0; i+b <= 40; i ++){
            if(dp[2][b+i]==2){
                if(i%2==0) printf("Masha\n");
                else printf("Stas\n");
                break;
            }
        }
        if(i+b>40) printf("Missing\n");
    }else{
        if(dp[a][b]==1) printf("Masha\n");
        else printf("Stas\n");
    }
    return 0;
}

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