51nod 最大子段和

start = 1
answerstart = asnwerend = 1
endmax = answer = a[1]
   for end = 2 to n do
        if endmax > 0 then
        endmax += a[end]
       else
       endmax = a[end]
       start = end
       endif
       if endmax > answer then
       answer = endmax
       answerstart = start
       answerend = end
       endif
  endfor

AC代码：

#include<bits/stdc++.h>
using namespace std;
int n;
const int maxn = 50005;
long long dp[maxn],a[maxn];
int main()
{
cin>>n;
for(int i=1;i<=n;i++)cin>>a[i];
int en=1,be=1;
dp[1]=1;
long long anbe=1,anen=1,enma=0,ans=1;
for(int i=1;i<=n;i++)
{
if(enma>=0)
{
enma+=a[i];
en=i;
}
else if(enma<0)
{
anbe=en;
enma=a[i];
}
if(enma>ans)
{
ans=enma;
anen=en;
anbe=be;
}
}
cout<<ans<<endl;
}