3206.交替组 I

Author: progzc

go-leetcode/classify_algorithm/array/leetcode_3206_alternating-groups-i/leetcode_3206_alternating-groups-i.go

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+package leetcode_3206_alternating_groups_i
+
+// 3206. 交替组 I
+// https://leetcode.cn/problems/alternating-groups-i
+
+// numberOfAlternatingGroups 顺序遍历
+// 时间复杂度: O(n)
+// 空间复杂度: O(1)
+func numberOfAlternatingGroups(colors []int) int {
+	var ans int
+	n := len(colors)
+	if n <= 2 {
+		return ans
+	}
+	for i := 0; i < n; i++ {
+		need := (colors[i] + 1) % 2
+		before := i - 1
+		after := i + 1
+		if before < 0 {
+			before = n - 1
+		}
+		if after > n-1 {
+			after = 0
+		}
+		if colors[before] == need && colors[after] == need {
+			ans++
+		}
+	}
+	return ans
+}