(LeetCode OJ) Maximum Subarray【53】

53. Maximum Subarray

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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.

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//典型的動態規劃問題：
//思路首先：
//很顯然在連續累加的過程中，加了nums[i]如果sum是小於0的，那麼說明前一次計算出的sums其副作用，需要重新尋找起始開始累加
//即重新以當前nums[i]為起始值開始累加
class Solution {
public:
    int maxSubArray(vector& nums) {
        int maxSum = nums[0];//記錄累加過程中的最大值
        int subSum = nums[0];
        for(int i = 1; i < nums.size(); i++)
        {
            subSum = subSum <= 0? nums[i] : subSum+nums[i];
            if(subSum > maxSum) 
                maxSum = subSum;
        }
        return maxSum;
    }
};