Merge pull request #1063 from 0xff-dev/2762

Add solution and test-cases for problem 2762

Author: 6boris

leetcode/2701-2800/2762.Continuous-Subarrays/README.md

@@ -0,0 +1,43 @@
+# [2762.Continuous Subarrays][title]
+
+## Description
+You are given a **0-indexed** integer array `nums`. A subarray of `nums` is called continuous if:
+
+- Let `i, i + 1, ..., j` be the indices in the subarray. Then, for each pair of indices `i <= i1, i2 <= j, 0 <= |nums[i1] - nums[i2]| <= 2`.
+
+Return the total number of **continuous** subarrays.
+
+A subarray is a contiguous **non-empty** sequence of elements within an array.
+
+**Example 1:**
+
+```
+Input: nums = [5,4,2,4]
+Output: 8
+Explanation: 
+Continuous subarray of size 1: [5], [4], [2], [4].
+Continuous subarray of size 2: [5,4], [4,2], [2,4].
+Continuous subarray of size 3: [4,2,4].
+Thereare no subarrys of size 4.
+Total continuous subarrays = 4 + 3 + 1 = 8.
+It can be shown that there are no more continuous subarrays.
+```
+
+**Example 2:**
+
+```
+Input: nums = [1,2,3]
+Output: 6
+Explanation: 
+Continuous subarray of size 1: [1], [2], [3].
+Continuous subarray of size 2: [1,2], [2,3].
+Continuous subarray of size 3: [1,2,3].
+Total continuous subarrays = 3 + 2 + 1 = 6.
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/continuous-subarrays
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/2701-2800/2762.Continuous-Subarrays/Solution.go

@@ -1,5 +1,98 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type SegmentTreeNode2762 struct {
+	Left, Right int
+	Min, Max    int
+	LeftChild   *SegmentTreeNode2762
+	RightChild  *SegmentTreeNode2762
+}
+
+func buildSegmentTree2762(arr []int, left, right int) *SegmentTreeNode2762 {
+	if left == right {
+		return &SegmentTreeNode2762{
+			Left:  left,
+			Right: right,
+			Min:   arr[left],
+			Max:   arr[left],
+		}
+	}
+
+	mid := (left + right) / 2
+	leftChild := buildSegmentTree2762(arr, left, mid)
+	rightChild := buildSegmentTree2762(arr, mid+1, right)
+
+	node := &SegmentTreeNode2762{
+		Left:       left,
+		Right:      right,
+		Min:        min(leftChild.Min, rightChild.Min),
+		Max:        max(leftChild.Max, rightChild.Max),
+		LeftChild:  leftChild,
+		RightChild: rightChild,
+	}
+
+	return node
+}
+
+func queryMin2762(node *SegmentTreeNode2762, left, right int) int {
+	if node.Left == left && node.Right == right {
+		return node.Min
+	}
+
+	mid := (node.Left + node.Right) / 2
+
+	if right <= mid {
+		return queryMin2762(node.LeftChild, left, right)
+	} else if left > mid {
+		return queryMin2762(node.RightChild, left, right)
+	} else {
+		leftMin := queryMin2762(node.LeftChild, left, mid)
+		rightMin := queryMin2762(node.RightChild, mid+1, right)
+		return min(leftMin, rightMin)
+	}
+}
+
+func queryMax2762(node *SegmentTreeNode2762, left, right int) int {
+	if node.Left == left && node.Right == right {
+		return node.Max
+	}
+
+	mid := (node.Left + node.Right) / 2
+
+	if right <= mid {
+		return queryMax2762(node.LeftChild, left, right)
+	} else if left > mid {
+		return queryMax2762(node.RightChild, left, right)
+	} else {
+		leftMax := queryMax2762(node.LeftChild, left, mid)
+		rightMax := queryMax2762(node.RightChild, mid+1, right)
+		return max(leftMax, rightMax)
+	}
+}
+
+func Solution(nums []int) int64 {
+	l := len(nums)
+	ans := int64(1)
+
+	tree := buildSegmentTree2762(nums, 0, l-1)
+	start := 0
+	var _max, _min int
+	for end := 1; end < l; end++ {
+		_max = queryMax2762(tree, start, end)
+		_min = queryMin2762(tree, start, end)
+		if _max-_min <= 2 {
+			ans += int64(end-start) + 1
+			continue
+		}
+		start++
+		for ; start <= end; start++ {
+			_max = queryMax2762(tree, start, end)
+			_min = queryMin2762(tree, start, end)
+			if _max-_min <= 2 {
+				break
+			}
+		}
+		ans += int64(end-start) + 1
+	}
+
+	return ans
 }

leetcode/2701-2800/2762.Continuous-Subarrays/Solution_test.go

@@ -10,12 +10,11 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs []int
+		expect int64
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{5, 4, 2, 4}, 8},
+		{"TestCase2", []int{1, 2, 3}, 6},
 	}
 
 	//	开始测试
@@ -30,10 +29,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }