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;}