OJ-Problems-Source/HDOJ/4272_autoAC.cpp

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#include <iostream>
#include <cstdio>
#include <algorithm>
#include <memory.h>
#define MIN(a , b) ((a) < (b) ? (a) : (b))
#define MAX(a , b) ((a) > (b) ? (a) : (b))
using namespace std;
const int maxn = 1300;
int x[maxn],stack[maxn],cnt[maxn];
bool dp[maxn][maxn],vis[maxn][maxn];
int n;
void read()
{
memset(cnt,0,sizeof(cnt));
memset(vis,false,sizeof(vis));
for(int i=0;i<n;i++)
{
scanf("%d",&stack[i]);
x[i] = stack[i];
}
return;
}
bool check()
{
if(n & 1) return false;
sort(x , x + n);
int m = x - unique(x , x + n);
for(int i=0;i<n;i++)
{
int idx = lower_bound(x , x + m , stack[i]) - x;
cnt[idx]++;
}
for(int i=0;i<m;i++)
{
if(cnt[i] & 1) return false;
}
return true;
}
bool dfs(int dep , int to , int st)
{
if(vis[dep][st]) return dp[dep][st];
bool flag = false;
int use = 0;
for(int i=dep-1;i>=0 && use < 5;i--)
{
if(st & (1 << (dep - i)))
{
use++;
if(stack[dep] == stack[i])
{
int cur = st;
cur ^= 1;
cur ^= (1 << (dep - i));
if(cur == 0)
{
flag = true;
break;
}
int pos = dep;
while((cur & 1) == 0)
{
cur >>= 1;
pos--;
}
int end = to-1;
while(end >= 0 && pos - end < 10)
{
cur |= (1 << (pos - end));
end--;
}
if(dfs(pos , end+1 , cur))
{
flag = true;
break;
}
}
}
}
vis[dep][st] = true;
return dp[dep][st] = flag;
}
int main()
{
while(~scanf("%d",&n))
{
read();
if(check() == false)
{
puts("0");
continue;
}
puts(dfs(n-1 , MAX(n-10 , 0) , (1 << MIN(10 , n)) - 1) ? "1" : "0");
}
return 0;
}