2026-03-27 21:33

Author: SilverRainZ

src/p/leetcode/index.rst

@@ -277,7 +277,9 @@ Invert Binary Tree
    :key: 二叉树
    :date: 2021-07-07 2026-03-23
 
-我能去 Google 了吗？[#]_
+我能 `去 Google`__ 了吗？
+
+__ https://twitter.com/mxcl/status/608682016205344768
 
 Best Time to Buy and Sell Stock II
 ----------------------------------
@@ -636,7 +638,7 @@ Trapping Rain Water
 
    `L[i]`, `R[i]` 为以第 `i` 格为中心，左右的最高点的高度，每一格可能容纳的水量为 `W[i] = min(L[i], R[i]) - Height[i]`。
 
-单调栈 [#]_
+`单调栈 <https://oi-wiki.org/ds/monotonous-stack/>`_
    利用单调栈的性质，维护一个由高到低的水洼左边，每次 pop 的时候，算该水洼里的一层水
 
 .. todo:: 还有 :math:`O(1)` 解法…… 歇会儿。
@@ -683,7 +685,7 @@ Reverse Linked List
    :diffculty: Easy
    :language: go
    :key: 链表
-   :date: 2021-07-16
+   :date: 2021-07-16 2026-03-23
    :reference: https://zhuanlan.zhihu.com/p/86745433
 
 :del:`没啥好说`。
@@ -891,8 +893,6 @@ Ones and Zeroes
 
 .. rubric:: 脚注
 
-.. [#] https://twitter.com/mxcl/status/608682016205344768
-.. [#] https://oi-wiki.org/ds/monotonous-stack/
 
 Merge Sorted Array
 ------------------
@@ -905,3 +905,63 @@ Merge Sorted Array
    :date: 2026-03-05
 
 很简单的一道题，要不先把 nums1 挪开然后直接合并，要不逆序。之前想复杂了。
+
+Remove Element
+--------------
+
+.. leetcode:: _
+   :id: remove-element
+   :diffculty: Easy
+   :language: go
+   :key: 数组
+   :date: 2026-03-27
+
+Remove Duplicates From Sorted Array
+-----------------------------------
+
+.. leetcode:: _
+   :id: remove-duplicates-from-sorted-array
+   :diffculty: Easy
+   :language: go
+   :key: 数组
+   :date: 2026-03-27
+
+Remove Duplicates From Sorted Array II
+--------------------------------------
+
+.. leetcode:: _
+   :id: remove-duplicates-from-sorted-array-ii
+   :diffculty: Medium
+   :language: go
+   :key: 数组
+   :date: 2026-03-27
+
+Majority Element
+----------------
+
+.. leetcode:: _
+   :id: majority-element
+   :diffculty: Easy
+   :language: go
+   :key: 数组
+   :date: 2026-03-27
+
+Boyer-Moore 算法。
+
+原理是：每次遇到两个不同的元素，就把它们“配对删除”。
+最坏的情况是每个 Majority Element 都和其他的元素配对了被删除，但也会剩下一个。
+
+Rotate Array
+------------
+
+.. leetcode:: _
+   :id: rotate-array
+   :diffculty: Medium
+   :language: go
+   :key: 数组
+   :date: 2026-03-27
+
+i 位置的元素往右挪动 k 个位置，被修改的下标序列会组成一个环：
+`[i, (i+k)%n (i+2k)%n, ... i]`。存在 `(i+x*k)%n == i`，即 `(x*k)%n == 0`。
+
+.. todo:: 环的数目为 `gcd(n, k)`

src/p/leetcode/majority-element/go.mod

@@ -0,0 +1,3 @@
+module majority-element
+
+go 1.26.1

src/p/leetcode/majority-element/main.go

@@ -0,0 +1,24 @@
+package main
+
+import "fmt"
+
+func majorityElement(nums []int) int {
+	var candicate, count int
+	for i := 0; i < len(nums); i++ {
+		if count == 0 {
+			candicate = nums[i]
+			count = 1
+		} else {
+			if candicate == nums[i]  {
+				count++
+			} else {
+				count--
+			}
+		}
+	}
+	return candicate
+}
+
+func main() {
+	fmt.Println(majorityElement([]int{2,2,1,1,1,2,2}))
+}

src/p/leetcode/maximum-subarray/go.mod

@@ -0,0 +1,3 @@
+module maximum-subarray
+
+go 1.26.1

src/p/leetcode/maximum-subarray/main.go

@@ -1,66 +1,19 @@
 package main
 
 // import "fmt"
-
-func maxSubArray(nums []int) int {
-	max := nums[0]
-	m := make([]int, len(nums))
-	for i, v := range nums {
-		if i == 0 || m[i-1] < 0 {
-			m[i] = v
-		} else if m[i-1]+v < 0 {
-			m[i] = v
-		} else {
-			m[i] = m[i-1] + v
-		}
-		if m[i] > max {
-			max = m[i]
-		}
-	}
-	return max
-}
-
-func maxSubArray_Conquer(nums []int, left bool) (int, int) {
-	if len(nums) == 1 {
-		// fmt.Println(nums, nums[0], nums[0], left)
-		return nums[0], nums[0]
-	}
-	lmax, lmid := maxSubArray_Conquer(nums[:len(nums)/2], true)
-	rmax, rmid := maxSubArray_Conquer(nums[len(nums)/2:], false)
-	max := lmid + rmid
-	if lmax > max {
-		max = lmax
-	}
-	if rmax > max {
-		max = rmax
-	}
-	var mid int
-	if left {
-		var tmp int
-		mid = nums[len(nums)-1]
-		for i := len(nums) - 1; i >= 0; i-- {
-			tmp += nums[i]
-			if tmp > mid {
-				mid = tmp
-			}
-		}
-	} else {
-		var tmp int
-		mid = nums[0]
-		for i := 0; i < len(nums); i++ {
-			tmp += nums[i]
-			if tmp > mid {
-				mid = tmp
+import "math"
+
+func maxSubArray_Foolish(nums []int) int {
+	max := -math.MaxInt64
+	for i := 0; i < len(nums); i ++ {
+		sum := 0
+		for j := i; j < len(nums); j++ {
+			sum += nums[j]
+			if sum > max {
+				max = sum
 			}
 		}
 	}
-
-	// fmt.Println(nums, max, mid, left)
-	return max, mid
-}
-
-func maxSubArray_Divide(nums []int) int {
-	max, _ := maxSubArray_Conquer(nums, true)
 	return max
 }
 
@@ -73,15 +26,4 @@ func main() {
 	println(maxSubArray([]int{-1, 1, 2, 3, -1}))
 	println(maxSubArray([]int{-2, -3, -1}))
 	println(maxSubArray([]int{8, -19, 5, -4, 20}))
-
-	println("------------")
-
-	println(maxSubArray_Divide([]int{-2, 1, -3, 4, -1, 2, 1, -5, 4}))
-	println(maxSubArray_Divide([]int{-1, -1, -1, -1}))
-	println(maxSubArray_Divide([]int{1}))
-	println(maxSubArray_Divide([]int{1, 2, 3}))
-	println(maxSubArray_Divide([]int{1, 2, 3, -1}))
-	println(maxSubArray_Divide([]int{-1, 1, 2, 3, -1}))
-	println(maxSubArray_Divide([]int{-2, -3, -1}))
-	println(maxSubArray_Divide([]int{8, -19, 5, -4, 20}))
 }

src/p/leetcode/new-problem.sh

@@ -17,3 +17,5 @@ $title_delim
 EOF
 
 mkdir $1
+cd $1
+go mod init $1

src/p/leetcode/remove-duplicates-from-sorted-array-ii/go.mod

@@ -0,0 +1,3 @@
+module remove-duplicates-from-sorted-array-ii
+
+go 1.26.1

src/p/leetcode/remove-duplicates-from-sorted-array-ii/main.go

@@ -0,0 +1,31 @@
+package main
+
+import "fmt"
+
+func removeDuplicates(nums []int) int {
+	if len(nums) < 3 {
+		return len(nums)
+	}
+	ptr := 1
+	for i := 2; i < len(nums); i++ {
+		if nums[i] == nums[ptr] && nums[i] == nums[ptr-1]{
+			continue
+		} else {
+			ptr++
+			nums[ptr] = nums[i]
+		}
+	}
+	return ptr+1
+}
+
+
+func main() {
+	nums := []int{0,0,1,1,1,1,2,3,3}
+	k := removeDuplicates(nums)
+	fmt.Println(k)
+	fmt.Println(nums[:k])
+	nums = []int{0}
+	k = removeDuplicates(nums)
+	fmt.Println(k)
+	fmt.Println(nums[:k])
+}

src/p/leetcode/remove-duplicates-from-sorted-array/go.mod

@@ -0,0 +1,3 @@
+module remove-duplicates-from-sorted-array
+
+go 1.26.1

src/p/leetcode/remove-duplicates-from-sorted-array/main.go

@@ -0,0 +1,21 @@
+package main
+
+import "fmt"
+
+func removeDuplicates(nums []int) int {
+	ptr := 0
+	for i := 1; i < len(nums); i++ {
+		if nums[i] == nums[ptr] {
+			continue
+		} else {
+			ptr++
+			nums[ptr] = nums[i]
+		}
+	}
+	return ptr+1
+}
+
+func main() {
+	nums := []int{0,0,1,1,1,2,2,3,3,4}
+	fmt.Println(removeDuplicates(nums))
+}