USACO 1.4 Mother's Milk

记忆化搜索即可……f[i][j][k]表示这个状态是否到达过……

/*
TASK:milk3
LANG:C++
*/
#include <iostream>
#include <cstdio>
using namespace std;

bool f[22][22][22] = {0};
bool ans[22] = {0};
int A, B, C;

inline void change(int &a,int &b, int B) // a->b
{
b = a + b;
a = 0;
if (b > B)
{
a = b - B;
b = B;
}
}

void dfs(int a, int b, int c)
{
f[a][b][c] = true;
if (!a) ans[c] = true;
int x = a, y = b, z = c;
change(x, y, B);
if (!f[x][y][z]) dfs(x, y, z);
x = a, y = b, z = c;
change(x, z, C);
if (!f[x][y][z]) dfs(x, y, z);
x = a, y = b, z = c;
change(y, x, A);
if (!f[x][y][z]) dfs(x, y, z);
x = a, y = b, z = c;
change(y, z, C);
if (!f[x][y][z]) dfs(x, y, z);
x = a, y = b, z = c;
change(z, x, A);
if (!f[x][y][z]) dfs(x, y, z);
x = a, y = b, z = c;
change(z, y, B);
if (!f[x][y][z]) dfs(x, y, z);
}

int main()
{
freopen("milk3.in", "r", stdin);
freopen("milk3.out","w", stdout);
cin >> A >> B >> C;
dfs(0, 0, C);
int outputbuff[22], t= 0;
for (int i = 0; i != 22; ++ i)
if (ans[i]) outputbuff[++t] = i;
for (int i = 1; i < t; ++ i) cout<<outputbuff[i]<<" ";
cout<<outputbuff[t]<<endl;
return 0;
}