【LeetCode从零单刷】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.

解答：

简单的动态规划。判断以前所有的努力是否对 当前元素 有正影响。

1. if (dp[i-1] + nums[i] > dp[i]) dp[i] = dp[i-1] + nums[i];
2. else dp[i] = nums[i];
3. 找到 dp 中的最大值。

class Solution {
public:
    int maxSubArray(vector<int>& nums) {
        if(nums.size() == 1){
            return nums[0];
        }

        int* dp = new int[nums.size()];
        dp[0] = nums[0];
        int max = dp[0];
        for(int i = 1; i < nums.size(); i++)
        {
            if(dp[i-1] + nums[i] > nums[i])
            {
                dp[i] = dp[i-1] + nums[i];
                if(max < dp[i]) max = dp[i];
            }
            else
            {
                dp[i] = nums[i];
                if(max < dp[i]) max = dp[i];
            }
        }
        return max;
    }
};