最長連續子序列

最長連續子序列
//方法一：利用動態規劃方法

#include<iostream>
	using namespace std;


	int main()
	{
		int N;
		long long int *a;


		while (cin >> N)
		{
			a = new long long int[N];
			long long int maxSum = LLONG_MIN;
			long long int sum = 0;
			for (int i = 0; i < N; i++)
			{
				cin >> a[i];
				if (sum > 0)
					sum += a[i];
				else
					sum = a[i];
				if (sum > maxSum)
					maxSum = sum;
			}
			cout << maxSum << endl;


			delete[] a;
		}


		//system("pause");
		return 0;
	}

//方法二：利用遍歷方法

#include<iostream>
	using namespace std;


	int main()
	{
		int N;
		long long int *a;


		while (cin >> N)
		{
			a = new long long int[N];
			for (int i = 0; i < N; i++)
				cin >> a[i];


			long long int maxSum = a[0];
			long long int sum;
			for (int i = 0; i < N; i++)
			{
				sum = 0;
				for (int j = i; j < N; j++)
				{
					sum += a[j];
					if (sum > maxSum)
						maxSum = sum;
				}
			}
			cout << maxSum << endl;


			delete[] a;
		}


		//system("pause");
		return 0;
	}

注意：遍歷方法可能會超時，時間複雜度爲O（N^2），動態規劃方法時間複雜度爲O（N）

OJ例題：http://ac.jobdu.com/problem.php?pid=1077