POJ 1141 Brackets Sequence

括号序列，刘汝佳黑书上的经典例题。但是这道题要输出我们最后得到的添加括号最少的序列，

输出序列确实很麻烦，参考了题解，才勉勉强强写出来，以后还得把这道题敲一遍。

/*Accepted    288K    32MS    C++    1862B    2012-07-23 11:46:07*/



#include<cstdio>

#include<cstring>

#include<cstdlib>

#include<algorithm>

using namespace std;

#define o -2

#define lr -3



const int MAXN = 105;

int f[MAXN][MAXN], record[MAXN][MAXN];

char s[MAXN];

const int inf = 0x3f3f3f3f;



bool judge( int l, int r)

{

    if( s[l] == '(' && s[r] == ')' || s[l] == '[' && s[r] == ']')

        return true;

    return false;

}



int dps(int l, int r)

{

    int &ans = f[l][r], i;

    if(ans != inf)

        return ans;

    if(l > r)

        return 0;

    if(l == r)

        return record[l][r] = o, ans = 1;

    for( i = l; i < r; i ++)

        if( dps(l, i) + dps(i + 1, r) < ans)

            ans = f[l][i] + f[i + 1][r], record[l][r] = i;

    if( judge(l, r) && dps(l + 1, r - 1) < ans)

        ans = f[l + 1][r - 1], record[l][r] = lr;

    return ans;

}



void print(int l, int r)

{

    switch( record[l][r])

    {

        case o :{

            if( s[l] == '(' || s[l] == '[')

            {

                printf( "%c", s[l]);

                print( l + 1, r);

                printf( s[l] == '(' ? ")" : "]");

            }

            else

            {

                printf(s[l] == ')' ? "(" : "[");

                printf("%c", s[l]);

                print(l + 1, r);

            }

            break;

        }

        case lr:{

            printf( "%c", s[l]);

            print(l + 1, r - 1);

            printf( "%c", s[r]);

            break;

        }

        case -1:

            return;

        default:

            print( l, record[l][r]), print(record[l][r] + 1, r);

            break;

    }

}



int main()

{

    while( scanf( "%s", s + 1) == 1)

    {

        memset(f, 0x3f, sizeof f);

        memset(record, -1, sizeof record);

        dps(1, strlen(s + 1));

        print(1, strlen(s + 1));

        printf( "\n");

    }

    return 0;

}