Find first subarray sum to zero

最新推荐文章于 2020-08-01 16:43:49 发布
转载 最新推荐文章于 2020-08-01 16:43:49 发布 · 907 阅读 · 0

本文介绍了一种算法，用于在包含正负数的数组中找到首个和为零的连续子数组。通过使用哈希表跟踪前缀和，算法在O(n)时间内解决了这一问题。

given an array with positive and negative numbers find the first continuous subarray that sums to 0


bool FindFirstPair(int& nStart, int& nEnd, int a[], int n)
{
        nStart = nEnd = n;
        int nCount = 0;
        hash_map<int, int> hash;
        bool bSet = false;
        for (int i = 0; i < n; i++)
        {
                nCount += a[i];
                if (0 == nCount)
                {
                        nStart = 0;
                        nEnd = i;
                        return true;
                }

                if (hash.find(nCount) == hash.end())
                        hash[nCount] = i;
                else
                {
                        int nIndex = hash[nCount];
                        if (nIndex+1 < nStart || (nIndex+1 == nStart && i - nIndex - 1 < nEnd - nStart))
                        {
                                nStart = nIndex+1;
                                nEnd = i;
                                bSet = true;
                        }
                }
        }

        return bSet;
}

有思路并不意味着做对，面试官看重 1，思路是否灵活；2，思维是否严谨


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