53 - Maximum Subarray

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

For example, given the array [−2,1,−3,4,−1,2,1,−5,4],

the contiguous subarray [4,−1,2,1] has the largest sum = 6.

click to show more practice.

More practice:

If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.

思路分析：

当前下标i的值nums[i] 和 包含当前下标nums[i]的值的前项和，比较两者大小

ret值表示当前最大值

/*
Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

For example, given the array [−2,1,−3,4,−1,2,1,−5,4],
the contiguous subarray [4,−1,2,1] has the largest sum = 6.
*/

#include "stdafx.h"
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

class Solution_053_MaximumSubarray
{
public:
	int maxSubArray(vector<int>& nums)
	{
		//−2,1,−3,4,−1,2,1,−5,4
		int n = nums.size();
		int ret = INT_MIN;
		int sum = 0;
		for (int i = 0; i < n; i++)
		{
			sum = max(sum + nums[i], nums[i]);
			ret = max(sum, ret);
		}

		return ret;
	}
};