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uva787.cpp
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uva787.cpp
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#include <iostream>
#include <vector>
#include <limits>
using namespace std;
long long arrayProduct(vector<int>& arr, int start, int end){
long long p = 1;
for(int i = start; i <= end; i++){
p *= arr[i];
}
return p;
}
long long biggestProduct(vector<int>& arr, int start, int end, bool thereIsZero = false){
//check for valid start and end
if(start > end || start < 0 || end > arr.size() - 1){
if(thereIsZero){
return 0;
}else{
return -std::numeric_limits<long long>::infinity();
}
}
//special case only one number (and if it is negative it can be a disaster without this line of code)
if(start == end){
if(thereIsZero){
return max(arr[0], 0);
}else{
return arr[0];
}
}
//check for zeros
for(int i = start; i <= end; i++){
if(arr[i] == 0){
if(thereIsZero){
return max(max(biggestProduct(arr, start, i-1, true), biggestProduct(arr, i+1, end, true)), 0);
}else{
return max(biggestProduct(arr, start, i-1, true), biggestProduct(arr, i+1, end, true));
}
}
}
//now negative numbers
vector<int> negIndexes;
for(int i = start; i <= end; i++){
if(arr[i] < 0){
negIndexes.push_back(i);
}
}
if(negIndexes.size() % 2 == 0){
return arrayProduct(arr, start, end);
}else{
int lastNegIndex = negIndexes[negIndexes.size() - 1];
int firstNegIndex = negIndexes[0];
return max(biggestProduct(arr, start, lastNegIndex - 1), biggestProduct(arr, firstNegIndex + 1, end));
}
}
int main(){
int n;
vector<int> arr;
while(!cin.eof()){
while(cin>>n && n != -999999 && !cin.eof()){
arr.push_back(n);
}
cout<<biggestProduct(arr, 0, arr.size() - 1)<<endl;
arr.clear();
}
}