LeetCode Maximum Subarray

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class Solution {public:    int maxSubArray(int A[], int n) {        int cur_sum = 0;        int max_sum = INT_MIN;                for (int i=0; i<n; i++) {            cur_sum += A[i];            if (cur_sum > max_sum) max_sum = cur_sum;            if (cur_sum < 0) {                cur_sum = 0;            }        }        return max_sum;    }};

老題

分治法，nlogn, 但是TLE

class Solution {public:int maxSubArray(int A[], int n) {        return dfs(A, 0, n);    }        int dfs(int A[], int start, int end) {        if (start >= end) {            cout<<"range error: start="<<start<<", end="<<end<<endl;            return INT_MIN;        }        if (start + 1 == end) return A[start];        int mid = (start + end) / 2;        int ma = dfs(A, start, mid);        int mb = dfs(A, mid, end);        int maxsum = ma > mb ? ma : mb;        int lsum = 0, rsum = 0;        int lmax = INT_MIN, rmax = INT_MIN;                for (int i=mid - 1; i>=0; i--) {            lsum += A[i];            if (lsum > lmax) lmax = lsum;        }                for (int i=mid; i<end; i++) {            rsum += A[i];            if (rsum > rmax) rmax = rsum;        }                if (lmax + rmax > maxsum) maxsum = lmax + rmax;        return maxsum;    };};