URAL 1152 False Mirrors 状压+记忆化搜索

英雄每秒钟可以摧毁三个连续的阳台(大Google给出的翻译。。 。 )，剩余阳台上的怪物每秒钟会对英雄造成一个单位的伤害。为英雄受到伤害的最小值是多少。

阳台数 n <= 20，且每个阳台只有两种状态。显然是状态压缩( 昨天尚神刚刚讲的→,→ )。

算了一下最多会用九秒钟，然后计算次数大约是这样(1<<20)*9，时限2000MS，所以尽情的暴力吧。

话说写代码的时候我正在看自己的位运算的博客. . . . . .然后南壕不屑的看了我一眼走了. . . . . .我没翻题解啊

状态转移方程  dp[ t ][ sta ] = min( dp[ t+1 ][ next_sta ] + next_sta中存在的怪兽和). 

#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <queue>
#include <cmath>
#include <stack>

#pragma comment(linker, "/STACK:1024000000");
#define LL long long int
#define ULL unsigned long long int
#define _LL __int64
#define INF 0x3f3f3f3f
#define Mod 1000000009

using namespace std;

int num[25];

int Min;

int dp[10][(1<<20)+10];

int dfs(int t,int sta,int n)
{
// cout<<"t = "<<t<<" sta = "<<sta<<endl;

if(t > 9)
return (1<<20);
if(dp[t][sta] != -1)
return dp[t][sta];

int i,temp,dag,j;

for(i = 0;i < n; ++i)
{
temp = sta;
if((temp&(1<<i)))
{
temp = (temp&(~(1<<i)));

//左2

if(i == 0)
{
temp = (temp&(~(1<<(n-1))));
temp = (temp&(~(1<<(n-2))));
dag = dfs(t+1,temp,n);
}
else if(i == 1)
{
temp = (temp&(~(1)));
temp = (temp&(~(1<<(n-1))));

dag = dfs(t+1,temp,n);
}
else
{
temp = (temp&(~(1<<(i-1))));
temp = (temp&(~(1<<(i-2))));

dag = dfs(t+1,temp,n);
}

for(j = 0;j < n; ++j)
{
if((temp&(1<<j)))
dag += num[j];
}

if(dp[t][sta] == -1 || dp[t][sta] > dag)
{
dp[t][sta] = dag;
}

temp = sta,dag = 0;

// 右2

if(i == n-1)
{
temp = (temp&(~(1<<(0))));
temp = (temp&(~(1<<(1))));
dag = dfs(t+1,temp,n);
}
else if(i == n-2)
{
temp = (temp&(~(1)));
temp = (temp&(~(1<<(n-1))));

dag = dfs(t+1,temp,n);
}
else
{
temp = (temp&(~(1<<(i+1))));
temp = (temp&(~(1<<(i+2))));

dag = dfs(t+1,temp,n);
}

for(j = 0;j < n; ++j)
{
if((temp&(1<<j)))
dag += num[j];
}

if(dp[t][sta] == -1 || dp[t][sta] > dag)
{
dp[t][sta] = dag;
}

temp = sta,dag = 0;

//左右各一

if(i == 0)
{
temp = (temp&(~(1<<(n-1))));
temp = (temp&(~(1<<(1))));
dag = dfs(t+1,temp,n);
}
else if(i == n-1)
{
temp = (temp&(~(1)));
temp = (temp&(~(1<<(n-2))));

dag = dfs(t+1,temp,n);
}
else
{
temp = (temp&(~(1<<(i-1))));
temp = (temp&(~(1<<(i-2))));

dag = dfs(t+1,temp,n);
}

for(j = 0;j < n; ++j)
{
if((temp&(1<<j)))
dag += num[j];
}

if(dp[t][sta] == -1 || dp[t][sta] > dag)
{
dp[t][sta] = dag;
}
}
}

return dp[t][sta];
}

int main()
{
//freopen("sadfsdaf.txt","w",stdout);
int n,i,sum = 0;

scanf("%d",&n);

for(i = 0;i < n; ++i)
{
scanf("%d",&num[i]);
sum += num[i];
}

Min = INF;

int sta = (1<<n)-1;

for(i = 0;i < 10; ++i)
{
memset(dp[i],-1,sizeof(int)*(sta+3));
}

for(i = 0;i <= 10; ++i)
{
dp[i][0] = 0;
}

dfs(0,sta,n);

int Min = (1<<20);

for(i = 0;i < 10; ++i)
{
if(dp[i][sta] != -1 && dp[i][sta] < Min)
Min = dp[i][sta];
}

printf("%d\n",Min);

return 0;
}