LeetCode/go/candy.go

package main

func candy(ratings []int) int {
	n := len(ratings)

	given, i := n, 1
	for i < n {
		if ratings[i-1] == ratings[i] {
			// same rating ⇒ no need for adjustments
			i++
			continue
		}

		// increasing rating
		localMax := 0
		for ; i < n && ratings[i-1] < ratings[i]; i++ {
			localMax += 1
			given += localMax
		}

		if i >= n {
			return given
		}

		// decreasing rating
		localMin := 0
		for ; i < n && ratings[i-1] > ratings[i]; i++ {
			localMin += 1
			given += localMin
		}

		// count the extrema only once
		given -= min(localMin, localMax)
	}

	return given
}