HDU 1848 Fibonacci again and again(SG函数)

#include<bits/stdc++.h>
using namespace std;
const int MAXN = 1001;
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < \'0\' || c > \'9\') {if(c == \'-\') f = -1; c = getchar();}
    while(c >= \'0\' && c <= \'9\') x = x * 10 + c - \'0\', c = getchar();
    return x * f;
}
int SG[MAXN], S[MAXN], Lim, N, f[MAXN] = {0, 1};
int main() {
    for(int i = 2; i <= 20; i++) f[i] = f[i - 1] + f[i - 2];
    N = 1001;
    for(int i = 1; i <= N; i++) {
        memset(S, 0, sizeof(S));
        for(int j = 1; j <= 20 && f[j] <= i; j++) S[SG[i - f[j]]] = 1;
        for(int j = 0; j <= N; j++) if(!S[j]) {SG[i] = j; break;}
    }
    int a, b, c;
    while(scanf(\"%d %d %d\", &a, &b, &c)) {
        if(!a && !b && !c) break;
        puts(SG[a] ^ SG[b] ^ SG[c] ? \"Fibo\" : \"Nacci\");
    }
    return 0;
}