取石子
取石子
https://ac.nowcoder.com/acm/problem/15972
设d[i][j]表示先手面临两堆石子分别为i,j时的取胜状态。
直接求SG函数即可。
实际上可以通过值看出来两堆石子和为奇数时候先手必胜,否则后手胜。
因为每次取的都为奇数并不会对总的石子数奇偶性造成改变。所以奇数时
即会有奇数轮,先手必胜。
#include <bits/stdc++.h> #include <unordered_map> using namespace std; typedef long long ll; typedef unsigned long long ull; #ifdef LOCAL #define debug(x) cout << "[" __FUNCTION__ ": " #x " = " << (x) << "]\n" #define TIME cout << "RuningTime: " << clock() << "ms\n", 0 #else #define TIME 0 #endif #define hash_ 1000000009 #define Continue(x) { x; continue; } #define Break(x) { x; break; } const int mod = 998244353; const int N = 1e5 + 10; const int INF = 0x3f3f3f3f; const ll LINF = 0x3f3f3f3f3f3f3f3f; #define gc p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1000000, stdin), p1 == p2) ? EOF : *p1++; inline int read(){ static char buf[1000000], *p1 = buf, *p2 = buf; register int x = false; register char ch = gc; register bool sgn = false; while (ch != '-' && (ch < '0' || ch > '9')) ch = gc; if (ch == '-') sgn = true, ch = gc; while (ch >= '0'&& ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = gc; return sgn ? -x : x; } ll fpow(ll a, int b, int mod) { ll res = 1; for (; b > 0; b >>= 1) { if (b & 1) res = res * a % mod; a = a * a % mod; } return res; } int d[110][110]; void dfs(int x, int y) { if (d[x][y] != -1) return ; if (x == 0 && y == 0) return void(d[x][y] = 1); int flag = 1; if (x > 9) dfs(x - 9, y), flag &= d[x - 9][y]; if (x > 3) dfs(x - 3, y), flag &= d[x - 3][y]; if (x > 1) dfs(x - 1, y), flag &= d[x - 1][y]; if (y > 9) dfs(x, y - 9), flag &= d[x][y - 9]; if (y > 3) dfs(x, y - 3), flag &= d[x][y - 3]; if (y > 1) dfs(x, y - 1), flag &= d[x][y - 1]; if (!flag) d[x][y] = 1; else d[x][y] = 0; return ; } int main() { #ifdef LOCAL freopen("E:/input.txt", "r", stdin); #endif memset(d, -1, sizeof d); for (int i = 1; i <= 100; i++) for (int j = 1; j <= 100; j++) { dfs(i, j); } int n1, n2; while (cin >> n1 >> n2) { printf("%s\n", d[n1][n2] ? "win" : "lose"); } return TIME; }