URAL 1183 Brackets Sequence

URAL 1183

思路：区间dp,打印路径，详见http://www.cnblogs.com/widsom/p/8321670.html

代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<algorithm>
using namespace std;
#define ll long long
#define pb push_back
#define mem(a,b) memset(a,b,sizeof(a))

const int N=105;
int dp[N][N];
int pos[N][N];
string s;
void dfs(int l,int r){
    if(l>r)return ;
    if(l==r){
        if(s[l]=='('||s[l]==')')cout<<"()";
        else cout<<"[]";
    }
    else{
        if(pos[l][r]==-1){
            cout<<s[l];
            dfs(l+1,r-1);
            cout<<s[r];
        }
        else{
            dfs(l,pos[l][r]);
            dfs(pos[l][r]+1,r);
        }
    }
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>s;
    for(int l=2;l<=s.size();l++){
        for(int i=0;i+l-1<s.size();i++){
            int j=i+l-1;
            if(s[i]=='('&&s[j]==')'||s[i]=='['&&s[j]==']')dp[i][j]=dp[i+1][j-1]+2,pos[i][j]=-1;
            for(int k=i;k<j;k++){
                if(dp[i][k]+dp[k+1][j]>=dp[i][j]){
                    dp[i][j]=dp[i][k]+dp[k+1][j];
                    pos[i][j]=k;
                }
            }
        }
    }
    dfs(0,s.size()-1);
    return 0;
}