按书上敲的......dp

#include<iostream>
using namespace std;

int MaxSum(int n, int a[])
{
	int sum = a[1], b = a[1];
	for(int i = 2; i <= n; i++)
	{
		if(b >= 0)
			b += a[i];
		else
			b = a[i];
		if(b > sum)
			sum = b;
	}
	
	return sum;
} 

int main()
{	
	int n;
	int a[200003];
	
	cin >> n;
	for(int i = 1; i <= n; i++)
		cin >> a[i];
	
	cout << MaxSum(n, a);

	return 0;
}