【BZOJ 4600】【SDOI 2016】硬币游戏
http://www.lydsy.com/JudgeOnline/problem.php?id=4600
转化成nim游戏
因为对于每一个反面朝上的硬币编号可以拆成\(2^a3^bc\),选择这个硬币可以翻的其他硬币的编号必须是c的倍数。
那么如果两个单一游戏的c不同的话,只要a和b相同,那么状态的sg值也相同,所以存sg函数的状态时不用考虑c,只用考虑a和b即可。
暴力枚举子状态进行转移。
小神说这是博弈里比较水的一道题QwQ
#include<cstdio>
#include<vector>
#include<cstring>
#include<algorithm>
using namespace std;
int in() {
int k = 0; char c = getchar();
for(; c < '0' || c > '9'; c = getchar());
for(; c >= '0' && c <= '9'; c = getchar())
k = k * 10 + c - 48;
return k;
}
vector <int> a;
int sg[23][23][23], n, maxq;
void init(int SG[23][23]) {
int p, q, t = 0, tmp, num;
for(int i = 0; i <= 20; ++i)
for(int j = 0; j <= 20; ++j) {
a.clear();
for(p = 1; p <= i; ++p, t = 0)
for(q = 1; q <= maxq && p * q <= i; ++q) {
t ^= SG[i - p * q][j];
a.push_back(t);
}
for(p = 1; p <= j; ++p, t = 0)
for(q = 1; q <= maxq && p * q <= j; ++q) {
t ^= SG[i][j - p * q];
a.push_back(t);
}
stable_sort(a.begin(), a.end());
if (!a.size() || a[0] != 0) continue;
tmp = num = 1;
while (tmp < a.size() && a[tmp] == a[tmp - 1]) ++tmp;
while (tmp < a.size()) {
if (a[tmp] != num) {
SG[i][j] = num;
break;
}
++tmp;
while (tmp < a.size() && a[tmp] == a[tmp - 1])
++tmp;
++num;
}
if (tmp == a.size()) SG[i][j] = num;
}
}
int T, m, pw2, pw3, ans;
int main() {
for(maxq = 1; maxq <= 20; ++maxq)
init(sg[maxq]);
T = in();
while (T--) {
n = in(); maxq = in(); ans = 0;
for(int i = 1; i <= n; ++i) {
if (in()) continue;
pw2 = pw3 = 0;
m = i;
while (m % 2 == 0) ++pw2, m /= 2;
while (m % 3 == 0) ++pw3, m /= 3;
ans ^= sg[maxq][pw2][pw3];
}
puts(ans ? "win" : "lose");
}
return 0;
}
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