lintcode/continuous-subarray-sum(AC).cpp at master · siXence/lintcode · GitHub

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class Solution {
public:
    /**
     * @param A an integer array
     * @return  A list of integers includes the index of
     *          the first number and the index of the last number
     */
    vector<int> continuousSubarraySum(vector<int>& A) {
        int n = A.size();
        int ll;
        int sum;
        int msum;

        ll = 0;
        msum = A[0];
        int i;
        for (i = 1; i < n; ++i) {
            if (A[i] > msum) {
                msum = A[i];
                ll = i;
            }
        }
        vector<int> ans;
        if (msum <= 0) {
            ans.push_back(ll);
            ans.push_back(ll);
            return ans;
        }

        int mll, mrr;
        ll = 0;
        msum = sum = 0;
        for (i = 0; i < n; ++i) {
            sum += A[i];
            if (sum < 0) {
                sum = 0;
                ll = i + 1;
            }
            if (sum > msum) {
                msum = sum;
                mll = ll;
                mrr = i;
            }
        }
        ans.push_back(mll);
        ans.push_back(mrr);
        return ans;
    }
};