【LeetCode】Maximum Subarray

Maximum Subarray 
Total Accepted: 20964 Total Submissions: 62498 My Submissions
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.
【解题思路】
最大连续子数组和。
初始值tempSum为0，扫描数组，如果tempSum<0，tempSum=A[i]，否则就累加。
每次和maxSum比较大小，取最大值。

Java AC 408ms

public class Solution {
    public int maxSubArray(int[] A) {
        int len = A.length;
        if(len == 1){
            return A[0];
        }
        int maxSum = A[0];
        int tempSum = 0;
        for(int i = 0; i < len ; i++){
            if(tempSum < 0){
                tempSum = A[i];
            }else if(tempSum >= 0){
                tempSum += A[i];
            }
            if(tempSum > maxSum){
                maxSum = tempSum;
            }
        }
        return maxSum;
    }
}

Python AC 300ms

class Solution:
    # @param A, a list of integers
    # @return an integer
    def maxSubArray(self, A):
        if A is None or len(A) == 0:
            return 0
        a_len = len(A)
        maxSum = A[0]
        tempSum = 0
        for i in range(a_len):
            if tempSum < 0:
                tempSum = A[i]
            else:
                tempSum += A[i]
            if tempSum > maxSum:
                maxSum = tempSum
        return maxSum