HDU 4628 Pieces (状压DP)

for(state=i;state>0;state=(state-1)&i)

#include <iostream>
#include <string.h>
#include <math.h>
#include <queue>
#include <algorithm>
#include <stdlib.h>
#include <map>
#include <set>
#include <stdio.h>
#include <time.h>
using namespace std;
#define LL long long
#define pi acos(-1.0)
#pragma comment(linker, "/STACK:1024000000")
#define root 1, n, 1
#define lson l, mid, rt<<1
#define rson mid+1, r, rt<<1|1
const int mod=1e9+7;
const int INF=0x3f3f3f3f;
const double eqs=1e-9;
const int MAXN=100000+10;
char s[20], s1[20];
int ok[1<<17], dp[1<<17];
void init()
{
memset(dp,INF,sizeof(dp));
int len=strlen(s);
int tot=1<<len, i, j, cnt, flag;
for(i=0;i<tot;i++){
cnt=0;
for(j=0;j<len;j++){
if(i&(1<<j)){
s1[cnt++]=s[j];
}
}
flag=0;
for(j=0;j<cnt/2;j++){
if(s1[j]!=s1[cnt-j-1]){
flag=1;
break;
}
}
ok[i]=1-flag;
}
}
int main()
{
int t, len, n, i, state;
scanf("%d",&t);
while(t--){
scanf("%s",s);
init();
len=strlen(s);
int tot=1<<len;
dp[0]=0;
for(i=0;i<tot;i++){
for(state=i;state>0;state=(state-1)&i){
if(ok[state])  dp[i]=min(dp[i],1+dp[state^i]);
}
}
printf("%d\n",dp[tot-1]);
}
return 0;
}