51nod oj 1050 循环数组最大子段和 【DP】

题目链接：1050

最大正子段和----与总和-最小负字段和------的最大值

代码：

#include<cstdio>#include<algorithm>using namespace std;int shu[110000];int main(){int n;scanf("%d",&n);long long sum,s=0,ss,ans;for (int i=0;i<n;i++){scanf("%d",&shu[i]);s+=shu[i];}ans=0,sum=0;ss=0;for (int i=0;i<n;i++){if (sum<0)sum=shu[i];elsesum+=shu[i];ss=max(ss,sum);}sum=0;for (int i=0;i<n;i++){if (sum>0)sum=shu[i];elsesum+=shu[i];ans=min(ans,sum);}ans=s-ans;ans=max(ans,ss);printf("%lld\n",ans);return 0;}