LintCode 265: Maximum Non-Negative Subarray

最大非负子数组求和

原创于 2020-06-27 14:23:42 发布 · 199 阅读

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#algorithm #算法

探讨了在给定整数数组中寻找连续的非负子数组，使其和最大，并返回该最大和的问题。通过算法解析，展示了如何有效解决此类问题。

265. Maximum Non-Negative Subarray

Given an integer arrayA, find the contiguous array (containing at least one number, and each numer is non negative), which has the largest sum and return its sum

Example

input:[1,2,-3,4,5,-6]

output:9

explation:

A[0]=1

A[1]=2

A[0]+A[1]=3

A[3]=4

A[4]=5

A[3]+A[4]=9

Notice

return -1 if each number of A is negative

1≤A.length≤10^5

0≤|A_i|≤1000

解法1：

class Solution {
public:
    /**
     * @param A: an integer array
     * @return: return maxium contiguous non-negative subarray sum
     */
    int maxNonNegativeSubArray(vector<int> &A) {
        int n = A.size();
        if (n == 0) return 0;
        int sum = 0, maxSum = 0;
        int posCount = 0;
        for (int i = 0; i < n; ++i) {
            
            if (A[i] < 0) {
                sum = 0;
             } else {
                sum += A[i];
                posCount++;
            } 

            if (maxSum < sum) {
                maxSum = sum;
            }

        }
        
        if (posCount == 0) return -1;
        return maxSum;
    }
};