连续子数组的最大和

#include<iostream>
#include<vector>
using namespace std;
int main()
{
vector<int> vec;
int tmp;
while(cin >> tmp)
vec.push_back(tmp);
if(vec.size()<=0)
return 0;
int sum=vec[0];
int sum_ac=0;
for(int i=0;i<vec.size();i++)
{
if(sum_ac<=0)
sum_ac=vec[i];
else
sum_ac+=vec[i];
if(sum<sum_ac)
sum=sum_ac;
}
return sum;
}