hdu 4628 Pieces（状压dp）

题目链接：hdu 4628 Pieces

代码

#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>

using namespace std;
const int maxn = 20;
const int maxs = (1<<16) + 6;
const int inf = 0x3f3f3f3f;

int N, dp[maxs], vis[maxs];
char str[maxn];

bool judge(int s) {
    int a[maxn], n = 0;
    for (int i = 0; i < N; i++) if (s&(1<<i))
        a[n++] = i;
    for (int i = 0; i < n/2; i++)
        if (str[a[i]] != str[a[n-i-1]]) return false;
    return true;
}

void init () {
    scanf("%s", str);
    N = strlen(str);
    memset(vis, 0, sizeof(vis));
    for (int i = 0; i < (1<<N); i++)
        if (judge(i)) vis[i] = 1;
}

int solve () {
    memset(dp, inf, sizeof(dp));
    dp[0] = 0;
    for (int i = 0; i < (1<<N); i++) {
        int s = i^((1<<N)-1);
        for (int j = s; j; j = (j-1)&s) {
            if (vis[j]) {
                int v = i|j;
                dp[v] = min(dp[v], dp[i]+1);
            }
        }
    }
    return dp[(1<<N)-1];
}

int main () {
    int cas;
    scanf("%d", &cas);
    while (cas--) {
        init();
        printf("%d\n", solve());
    }
    return 0;
}