135. Candy

class Solution {
public:
    int candy(vector<int>& ratings) {
        int n = ratings.size();
        vector<int> candy(n, 1);

        for (int i = 1; i < n; ++i) {
            if (ratings[i] > ratings[i - 1]) {
                candy[i] = candy[i - 1] + 1;
            }
        }

        for (int i = n - 2; i >= 0; --i) {
            if (ratings[i] > ratings[i + 1]) {
                candy[i] = max(candy[i], candy[i + 1] + 1);
            }
        }
        return accumulate(candy.begin(), candy.end(), 0);
    }
};

• T: $O(N)$
• S: $O(N)$