C :

#include <stdio.h>
#include <stdlib.h>
#define maxn 100010

int A[maxn];
int dp[maxn];

int main()
{
    int N;
    scanf("%d",&N);
    for(int i = 0;i < N; i++)scanf("%d",&A[i]);
    int ans = A[0];
    dp[0]=A[0];
    for(int i = 1;i < N; i++) {
        if(dp[i-1]>0)dp[i] = dp[i-1] + A[i];
        else dp[i] = A[i];
        ans = ans < dp[i]?dp[i]:ans;
    }
    printf("%d\n",ans);


    return 0;
}

C++ :

#include <iostream>
#include <cstdlib>
#include <algorithm>

using namespace std;

int n, li[10000000], sum = -0xfffff, l = 0;


int main()
{
	cin >> n;
	for (int i = 1; i <= n; i ++)
		cin >> li[i];
		
	for (int i = 1; i <= n; i ++)
	{
		l += li[i];
		if (l < 0)
			l = 0;
		sum = max (sum, l);
	}
	
	cout << sum;
	//system ("pause");
	return 0;
}

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int[] A=new int[n];
		for(int i=0;i<n;i++) A[i]=sc.nextInt();
		int maxsum=A[0], premax=A[0];
		for(int i=1;i<n;i++) {
			if(premax>0) premax+=A[i];
			else premax=A[i];
			if(premax>maxsum) maxsum=premax;		
		}
		System.out.println(maxsum);
	}

}