UVa10651(记忆化搜索)

题意:

给一串-和o组成的字符串，你可以把“-oo"变成”o--"，可以把“oo-”变成“--o",问最后最少有多少个o.

状态压缩 ，记忆化搜索

code:

#include <stdio.h>

#include <string.h>

#define len 12

#define min(a,b) (((a)<(b)) ?(a):(b))

int d[1<<13];

int dp(int n)

{

    int i, t;

    if(d[n]!=-1) return d[n];

    d[n] = 0;

    for(i=0; i<len; i++)

        if(n&(1<<i))

            d[n]++;

    for(i=0; i<len-2; i++)

    {

        t = n;

        if( (t&(1<<i)) && (t&(1<<(i+1))) && !(t&(1<<(i+2))) )

        {

            t &=~(1<<i);

            t &=~(1<<(i+1));

            t |=1<<(i+2);

            d[n] = min(d[n],dp(t));

        }

        if( !(t&(1<<i)) && (t&(1<<(i+1))) && (t&(1<<(i+2))) )

        {

            t &=~(1<<(i+1));

            t &=~(1<<(i+2));

            t |=1<<i;

            d[n] = min(d[n],dp(t));

        }

    }

    return d[n];

}

int main()

{

    int T, i, n;

    char str[20];

    scanf("%d",&T);

    while(T--)

    {

        scanf("%s",str);

        n = 0;

        for(i=0; i<len; i++)

            if(str[i]=='o')

                n ^=1<<i;

        memset(d,-1,sizeof(d));

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

    }

    return 0;

}