[LeetCode]Maximum Subarray

最新推荐文章于 2021-10-21 15:55:14 发布

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本文介绍了一种求解一维数组中最大子数组和的线性时间复杂度算法实现。通过遍历数组并使用局部变量跟踪当前子数组之和，该方法能够在O(n)的时间复杂度内找到具有最大和的连续子数组。

class Solution {
//OJ suggest to solve this problem using D&C, but its time complexity is O(nlogn), right?
//So I choose the O(n) version to implement
public:
	int maxSubArray(int A[], int n) {
		// Start typing your C/C++ solution below
		// DO NOT write int main() function
		if(0 == n) return 0;
		int ans = A[0];
		int local = 0;
		for (int i = 0; i < n; ++i)
		{
			local = local > 0 ? local+A[i] : A[i];
			ans = max(local, ans);
		}
		return ans;
	}
};

second time

class Solution {
public:
    int maxSubArray(int A[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(n == 0) return 0;
        int curSum = A[0];
        int maxSum = curSum;
        for(int i = 1; i < n; ++i)
        {
            if(curSum+A[i] > A[i]) curSum = curSum+A[i];
            else curSum = A[i];
            maxSum = max(maxSum, curSum);
        }
        
        return maxSum;    
    }
};