1049 Maximum subsegment sum

1049 Maximum subsegment sum 

Base Time Limit: 1 second Space Limit: 131072 KB Score: 0  Difficulty: Basic

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A sequence a[1],a[2],a[3],…,a[n] composed of N integers, find the sequence such as a[i]+a[i+1]+…+a[j] The maximum value of the sum of consecutive subsections of . The sum is 0 when all of the given integers are negative.

 

For example: -2,11,-4,13,-5,-2, and the largest subsegments are: 11,-4,13. and 20.

Input

Line 1: Length N of integer sequences (2 <= N <= 50000)
Lines 2 - N+1: N integers (-10^9 <= A[i] <= 10^9)

Output

Output the maximum subsection sum.

Input example

6
-2
11
-4
13
-5
-2

Output example

20 

dp past, find the largest.

 1 #include<iostream>
 2 using namespace std;
 3 int a[500050];
 4 int main(){
 5     int n;
 6     cin>>n;
 7     for(int i=0;i<n;i++) 
 8         cin>>a[i];
 9     long long sum=0,maxn=0,ss=0;
10     for(int i=0;i<n;i++){
11         sum+=a[i];
12         sum=max(sum,ss);
13         maxn=max(maxn,sum);
14     }
15     cout<<maxn<<endl;
16     return 0;
17 }