Leetcode#135 Candy

 1 int candy(vector<int> &ratings) {
 2   int n = ratings.size();
 3   int sum = 1;
 4   int len = 0;
 5   int prev = 1;
 6 
 7   for (int i = 1; i < n; i++) {
 8     if (ratings[i] == ratings[i - 1]) {
 9       prev = 1;
10       len = 0;
11       sum += prev;
12     }
13     else if (ratings[i] > ratings[i - 1]) {
14       prev++;
15       len = 0;
16       sum += prev;
17     }
18     else if (ratings[i] < ratings[i - 1]) {
19       prev--;
20       len++;
21       sum += prev;
22       if (i == n - 1 || ratings[i] <= ratings[i + 1]) {
23         sum += prev < 1 ? (1 - prev) * (len + 1) : (1 - prev) * len;
24         prev = 1;
25       }
26     }
27   }
28 
29   return sum;
30 }