【LeetCode】Maximum Subarray

题意:

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.

思路：

很直接的最长上升子序列，线性 dp, dp 式子为：

dp[i] = dp[i-1] > 0?(A[i] + dp[i-1]):A[i]

然后迭代更新最大值就好。（会不会觉得 python 的实现写得很不一样？）

代码：

C++：

class Solution {
public:
    int maxSubArray(int A[], int n) {
        int ans = A[0];
        int *dp = new int[n];
        dp[0] = A[0];

        for(int i = 1;i < n;++i)
        {
            dp[i] = dp[i-1]>0?(A[i] + dp[i-1]):A[i];
            if(dp[i] > ans)
                ans = dp[i];
        }

        return ans;
    }
};

Python：

class Solution:
    # @param A, a list of integers
    # @return an integer
    def maxSubArray(self, A):
        ans = A[0]
        n = len(A)
        for i in range(1,n):
            if A[i-1] > 0:
                A[i] = A[i-1] + A[i]

            if A[i] > ans:
                ans = A[i]
        return ans