HDU 1848

http://acm.hdu.edu.cn/showproblem.php?pid=1848

利用计算grundy数组，把一类博弈转化为nim博弈，最后x不为0为先手必胜态

#include <iostream>

#include <cstdio>

#include <cstring>

#include <set>

#include <algorithm>

using namespace std ;



//N堆硬币，每堆Xi

//每次从一堆中取a1 a2...ak，先取完胜 



const int MAX_X=1005;

const int MAX_K=25;

const int MAX_N=5;



int N, K, X[MAX_N], A[MAX_K];



int grundy[MAX_X]; 



void solveSG() {

    grundy[0] = 0;

    //int max_x = *max_element(X, X + N);

    for(int j = 1; j <= 1000; j++) {

        set <int> s;

        for(int i = 0; i < 20; i++){  //A[i] <= j

            if(A[i] <= j) s.insert(grundy[j-A[i]]);

        }

        int g = 0;

        while(s.count(g)) g++;

        grundy[j] = g;

    }

    /*

    int x = 0;

    for(int i = 0; i < N; i++) x ^= grundy[X[i]];

    if(x) puts("Fibo");//先手胜

    else puts("Nacci");//后手胜 

    */

} 



int main() {

    A[0] = A[1] = 1;

    for(int i = 2; i < 20; i++)

        A[i] = A[i-1] + A[i-2];

    solveSG();

    while(~scanf("%d%d%d", &X[0], &X[1], &X[2])) {

        if(!X[0] && !X[1] && !X[2]) break;

        int x = 0;

        for(int i = 0; i < 3; i++) x ^= grundy[X[i]];

        if(x) puts("Fibo");//先手胜

        else puts("Nacci");//后手胜 

    }

    return 0;

}

View Code