delete brackets

https://ac.nowcoder.com/acm/problem/21303

 

 

 

n^3 positive solution http://www.perfectpan.org/archives/2520

 

My own n^5 stupid code

#include <stdio.h>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxn=1e2+10;
  
int dp[maxn][maxn][maxn];
int pre[maxn];
char ch1[maxn],ch2[maxn];
int n1,n2;
  
bool judge(int p,int l,int r)
{
    int i;
    for(i=l;i<=r;i++){
        if(p+pre[i]-pre[l-1]<0) return 0;
    }
    return 1;
}
  
int main()
{
    int i,j,k,l,flag;
    scanf("%s%s",ch1+1,ch2+1);
    n1=strlen(ch1+1),n2=strlen(ch2+1);
    for(i=1;i<=n1;i++){
        pre[i]=pre[i-1];
        if(ch1[i]=='(') pre[i]++;
        else pre[i]--;
    }
    memset(dp,0,sizeof(dp));
    dp[0][0][0]=1; 
    for(i=1;i<=n2;i++){//dp[i-1][k][] -> dp[i][j][]
        for(j=i;j+(n2-i)<=n1;j++){
            if(ch2[i]==ch1[j]){
                for(k=0;k<=j-1;k++){
                    if(ch2[i-1]==ch1[k]){
                        for(l=0;l<=k;l++){
                            //if(judge(l,k+1,j-1)){
                            //if(l+pre[j-1]-pre[k]>=0){
                            if(judge(l,k+1,j-1)&&l+pre[j-1]-pre[k]==0){
                                dp[i][j][l+pre[j-1]-pre[k]]|=dp[i-1][k][l];
                                //if(dp[i-1][k][l]) printf("*%d %d %d %d %d %d*\n",i,j,l+pre[j-1]-pre[k],i-1,k,l);
                            }
                        }
                    }
                }
            }
        }
    }
    flag=0;
    for(j=1;j<=n1;j++){
        flag|=dp[n2][j][0];
    }
    if(flag) printf("Possible\n");
    else printf("Impossible\n");
    return 0;
}