ACM-ICPC 2018 沈阳赛区网络预赛 Call of Accepted

题目链接：Call of Accepted

题解：dfs根据优先级先后计算。参考博客

#include<string.h>
#include<bits/stdc++.h>
#include<algorithm>
#include<queue>
#define ll long long
using namespace std;
#define INF 0xffffff
#define MAXN 300010
const int N=1e2+50;
char s[N];
bool v[N][N][2];
ll val[N][N][2];
int p[N];
stack<int>st;
ll dfs(int l,int r,int f)
{
    if(v[l][r][f])return val[l][r][f];
    v[l][r][f]=1;
    int cnt=0;
    for(int i=r;i>=l;i--)
    {
        if(s[i]=='(')cnt--;
        if(s[i]==')')cnt++;
        if(s[i]=='+'&&!cnt)
        {
            if(f==0)return val[l][r][f]=dfs(l,i-1,0)+dfs(i+1,r,0);
            else return val[l][r][f]=dfs(l,i-1,1)+dfs(i+1,r,1);
        }
        else if(s[i]=='-'&&!cnt)
        {
            if(f==0)return val[l][r][f]=dfs(l,i-1,0)-dfs(i+1,r,1);
            else return val[l][r][f]=dfs(l,i-1,1)-dfs(i+1,r,0);
        }
    }
    cnt=0;
    for(int i=r;i>=l;i--)
    {
         if(s[i]=='(')cnt--;
        if(s[i]==')')cnt++;
        if(s[i]=='*'&&!cnt)
        {
            if(f==0)
            {
                val[l][r][f]=dfs(l,i-1,0)*dfs(i+1,r,0);
                val[l][r][f]=min(val[l][r][f],dfs(l,i-1,0)*dfs(i+1,r,1));
                val[l][r][f]=min(val[l][r][f],dfs(l,i-1,1)*dfs(i+1,r,0));
                return val[l][r][f]=min(val[l][r][f],dfs(l,i-1,1)*dfs(i+1,r,1));

            }
            else
            {
                val[l][r][f]=dfs(l,i-1,0)*dfs(i+1,r,0);
                val[l][r][f]=max(val[l][r][f],dfs(l,i-1,0)*dfs(i+1,r,1));
                val[l][r][f]=max(val[l][r][f],dfs(l,i-1,1)*dfs(i+1,r,0));
                return val[l][r][f]=max(val[l][r][f],dfs(l,i-1,1)*dfs(i+1,r,1));
            }
        }
    }
    cnt=0;
    for(int i=r;i>=l;i--)
    {
        if(s[i]=='(')cnt--;
        if(s[i]==')')cnt++;
        if(s[i]=='d'&&!cnt)
        {
              if(f==0)return val[l][r][f]=dfs(l,i-1,0);
              else return val[l][r][f]=dfs(l,i-1,1)*dfs(i+1,r,1);
        }
    }
    if(s[l]=='('&&p[l]==r)return val[l][r][f]=dfs(l+1,p[l]-1,f);
    ll sum=0;
    for(int i=l;i<=r;i++)
    {
        sum=sum*10+s[i]-'0';
    }
    //cout<<"$$$"<<sum<<endl;
    return val[l][r][f]=sum;

}
int main()
{
    while(scanf("%s",s+1)!=EOF)
    {
        memset(v,0,sizeof(v));
        int len=strlen(s+1);
        for(int i=1;i<=len;i++)
        {
            if(s[i]=='(')st.push(i);
            if(s[i]==')')
            {
               int  tmp=st.top();
               st.pop();
               p[tmp]=i;
            }
        }
        //cout<<dfs(1,len,0)<<endl;
        printf("%lld %lld
",dfs(1,len,0),dfs(1,len,1));
    }
    return 0;
}