53. Maximum Subarray

53. Maximum Subarray

题目

 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.

解析

• 两个if的先后顺序

// add 53. Maximum Subarray
class Solution {
public:
	int maxSubArray(vector<int>& nums) {

		int ret = INT_MIN;
		int temp = 0;
		for (int i = 0; i < nums.size();i++)
		{
			temp += nums[i];

			if (temp>ret) // //两个if的先后顺序
			{
				ret = temp;
			}

			if (temp < 0)
			{
				temp = 0;
			}
		}
		return ret;
	}

	int maxSubArray(int A[], int n) {
		vector<int> vec(A,A+n);
		return maxSubArray(vec);
	}
};

题目来源

• 53. Maximum Subarray
• 01-复杂度1 最大子列和问题(剑指offer和PAT)