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| #include <iostream>
#include <memory.h>
#include <cmath>
#include <stack>
using namespace std;
long dp[10][10][2];
bool visit[10][10];
string str;
int setPostfix(string str) {
stack<int> s;
stack<char> op;
for(int i = 0; i < str.length(); i++) {
if ('0' <= str[i] && str[i] <= '9') {
s.push(str[i] & 0b1111);
}
else {
if(op.empty()) {
op.push(str[i]);
} else {
if(op.top() == '*' && str[i] != '*') {
int a, b;
a = s.top();
s.pop();
b = s.top();
s.pop();
s.push(a * b);
op.pop();
}
if(!op.empty() && op.top() == '-') {
int a = s.top();
a *= -1;
s.pop();
s.push(a);
op.pop();
op.push('+');
}
op.push(str[i]);
}
}
}
while(!op.empty()) {
int a, b;
a = s.top();
s.pop();
b = s.top();
s.pop();
switch (op.top()) {
case '+' : s.push(b + a); break;
case '-' : s.push(b - a); break;
case '*' : s.push(b * a); break;
}
op.pop();
}
return s.top();
}
pair<long,long> calc(int f, int e) {
if(visit[f][e]) return make_pair(dp[f][e][0],dp[f][e][1]);
visit[f][e] = true;
dp[f][e][0] = dp[f][e][1] = setPostfix(str.substr(2*f, (e-f)*2+1));
for(int i = f; i < e; i++){
switch (str[i*2+1]) {
case '+' :
dp[f][e][0] = max(dp[f][e][0], max(calc(f,i).first, calc(f,i).second) + max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], max(calc(f,i).first, calc(f,i).second) + min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], min(calc(f,i).first, calc(f,i).second) + max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], min(calc(f,i).first, calc(f,i).second) + min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], max(calc(f,i).first, calc(f,i).second) + max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], max(calc(f,i).first, calc(f,i).second) + min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], min(calc(f,i).first, calc(f,i).second) + max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], min(calc(f,i).first, calc(f,i).second) + min(calc(i+1,e).first,calc(i+1,e).second)); break;
case '-' :
dp[f][e][0] = max(dp[f][e][0], max(calc(f,i).first, calc(f,i).second) - max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], max(calc(f,i).first, calc(f,i).second) - min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], min(calc(f,i).first, calc(f,i).second) - max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], min(calc(f,i).first, calc(f,i).second) - min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], max(calc(f,i).first, calc(f,i).second) - max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], max(calc(f,i).first, calc(f,i).second) - min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], min(calc(f,i).first, calc(f,i).second) - max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], min(calc(f,i).first, calc(f,i).second) - min(calc(i+1,e).first,calc(i+1,e).second)); break;
case '*' :
dp[f][e][0] = max(dp[f][e][0], max(calc(f,i).first, calc(f,i).second) * max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], max(calc(f,i).first, calc(f,i).second) * min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], min(calc(f,i).first, calc(f,i).second) * max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][0] = max(dp[f][e][0], min(calc(f,i).first, calc(f,i).second) * min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], max(calc(f,i).first, calc(f,i).second) * max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], max(calc(f,i).first, calc(f,i).second) * min(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], min(calc(f,i).first, calc(f,i).second) * max(calc(i+1,e).first,calc(i+1,e).second));
dp[f][e][1] = min(dp[f][e][1], min(calc(f,i).first, calc(f,i).second) * min(calc(i+1,e).first,calc(i+1,e).second)); break;
}
}
return make_pair(dp[f][e][0],dp[f][e][1]);
}
int main() {
int n;
cin>>n>>str;
cout<<max(calc(0,(str.length()-1)/2).first, calc(0,(str.length()-1)/2).second);
}
|
