diff --git a/leetcode/1154.go b/leetcode/1154.go
new file mode 100644
index 0000000..7b01155
--- /dev/null
+++ b/leetcode/1154.go
@@ -0,0 +1,25 @@
+package main
+
+import "strconv"
+
+func dayOfYear(date string) int {
+	year, _ := strconv.Atoi(date[:4])
+	month, _ := strconv.Atoi(date[5:7])
+	day, _ := strconv.Atoi(date[8:])
+	monthDays := []int{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
+	if year%4 == 0 {
+		monthDays[1] = 29
+	}
+	if year%100 == 0 {
+		monthDays[1] = 28
+	}
+	if year%400 == 0 {
+		monthDays[1] = 29
+	}
+	res := 0
+	for i := 0; i < month-1; i++ {
+		res += monthDays[i]
+	}
+	res += day
+	return res
+}
diff --git a/leetcode/1349.go b/leetcode/1349.go
new file mode 100644
index 0000000..099f1bc
--- /dev/null
+++ b/leetcode/1349.go
@@ -0,0 +1,50 @@
+package main
+
+func maxStudents(seats [][]byte) int {
+	l := len(seats[0])
+	dp := make([]int, 1<<l)
+	for _, seat := range seats {
+		s := byte(0)
+		for _, tmp := range seat {
+			switch tmp {
+			case '.':
+				s = (s << 1) | 1
+			case '#':
+				s = s << 1
+			}
+		}
+		newDp := make([]int, 1<<l)
+
+		for iInt := 0; iInt < 1<<l; iInt++ {
+			i := byte(iInt)
+			if (i^s)&i != 0 || i&(i<<1) != 0 || i&(i>>1) != 0 {
+				continue
+			}
+			add := 0
+			for k := 0; k < l; k++ {
+				if (1<<k)&i != 0 {
+					add += 1
+				}
+			}
+
+			for jInt := 0; jInt < 1<<l; jInt++ {
+				j := byte(jInt)
+				if i&(j<<1) != 0 || i&(j>>1) != 0 {
+					continue
+				}
+
+				if dp[j]+add > newDp[i] {
+					newDp[i] = dp[j] + add
+				}
+			}
+		}
+		dp = newDp
+	}
+	res := 0
+	for _, x := range dp {
+		if x > res {
+			res = x
+		}
+	}
+	return res
+}
diff --git a/leetcode/1660.go b/leetcode/1660.go
new file mode 100644
index 0000000..ae67310
--- /dev/null
+++ b/leetcode/1660.go
@@ -0,0 +1,33 @@
+package main
+
+func isWinner(player1 []int, player2 []int) int {
+	score1, score2 := 0, 0
+	lastIdx := -10
+	for i := 0; i < len(player1); i++ {
+		if i-lastIdx <= 2 {
+			score1 += player1[i]
+		}
+		score1 += player1[i]
+		if player1[i] == 10 {
+			lastIdx = i
+		}
+	}
+
+	lastIdx = -10
+	for i := 0; i < len(player2); i++ {
+		if i-lastIdx <= 2 {
+			score2 += player2[i]
+		}
+		score2 += player2[i]
+		if player2[i] == 10 {
+			lastIdx = i
+		}
+	}
+
+	if score1 > score2 {
+		return 1
+	} else if score2 > score1 {
+		return 2
+	}
+	return 0
+}
diff --git a/leetcode/1671.go b/leetcode/1671.go
new file mode 100644
index 0000000..e34437a
--- /dev/null
+++ b/leetcode/1671.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+)
+
+func minimumMountainRemovals(nums []int) int {
+	res := 0
+	leftUp := make([]int, len(nums))
+	for i := 0; i < len(nums); i++ {
+		leftUp[i] = 1
+		for j := i - 1; j >= 0; j-- {
+			if nums[j] < nums[i] && leftUp[i] < leftUp[j]+1 {
+				leftUp[i] = leftUp[j] + 1
+			}
+		}
+	}
+	rightUp := make([]int, len(nums))
+	for i := len(nums) - 1; i >= 0; i-- {
+		rightUp[i] = 1
+		for j := i + 1; j < len(nums); j++ {
+			if nums[j] < nums[i] && rightUp[j]+1 > rightUp[i] {
+				rightUp[i] = rightUp[j] + 1
+			}
+		}
+	}
+
+	for i := 0; i < len(nums); i++ {
+		if leftUp[i] > 1 && rightUp[i] > 1 && leftUp[i]+rightUp[i]-1 > res {
+			res = leftUp[i] + rightUp[i] - 1
+		}
+	}
+	return len(nums) - res
+}
+
+func main() {
+	nums := []int{23, 47, 63, 72, 81, 99, 88, 55, 21, 33, 32}
+	fmt.Println(minimumMountainRemovals(nums))
+}
diff --git a/leetcode/1726.go b/leetcode/1726.go
new file mode 100644
index 0000000..08e2de3
--- /dev/null
+++ b/leetcode/1726.go
@@ -0,0 +1,23 @@
+package main
+
+import "sort"
+
+func tupleSameProduct(nums []int) int {
+	cnt := map[int]int{}
+	sort.Ints(nums)
+	for i := 0; i < len(nums); i++ {
+		for j := i + 1; j < len(nums); j++ {
+			s := nums[i] * nums[j]
+			if v, ok := cnt[s]; ok {
+				cnt[s] = v + 1
+			} else {
+				cnt[s] = 1
+			}
+		}
+	}
+	res := 0
+	for _, v := range cnt {
+		res += v * (v - 1) * 4
+	}
+	return res
+}
diff --git a/leetcode/2316.go b/leetcode/2316.go
new file mode 100644
index 0000000..7cdf246
--- /dev/null
+++ b/leetcode/2316.go
@@ -0,0 +1,51 @@
+package main
+
+func countPairs2316(n int, edges [][]int) int64 {
+	parent := make([]int, n)
+	for i := range parent {
+		parent[i] = i
+	}
+	find := func(x int) int {
+		tmp := x
+		for parent[x] != x {
+			x = parent[x]
+		}
+		for parent[tmp] != x {
+			parent[tmp], tmp = x, parent[tmp]
+		}
+		return x
+	}
+
+	union := func(x, y int) {
+		x = find(x)
+		y = find(y)
+		parent[x] = y
+	}
+
+	for _, edge := range edges {
+		union(edge[0], edge[1])
+	}
+
+	m := map[int]int{}
+	for i := range parent {
+		m[find(i)]++
+	}
+
+	groups := make([]int, 0, len(m))
+	for _, v := range m {
+		groups = append(groups, v)
+	}
+	sums := make([]int, len(m))
+	s := 0
+	for i := len(groups) - 1; i >= 0; i-- {
+		sums[i] = s
+		s += groups[i]
+	}
+
+	res := int64(0)
+	for i, g1 := range groups {
+		res += int64(g1) * int64(sums[i])
+	}
+
+	return res
+}
diff --git a/leetcode/2706.go b/leetcode/2706.go
new file mode 100644
index 0000000..779d946
--- /dev/null
+++ b/leetcode/2706.go
@@ -0,0 +1,20 @@
+package main
+
+import "math"
+
+func buyChoco(prices []int, money int) int {
+	minMoneys := [2]int{math.MaxInt, math.MaxInt}
+	for _, price := range prices {
+		if price < minMoneys[0] {
+			minMoneys[1], minMoneys[0] = minMoneys[0], price
+			continue
+		}
+		if price < minMoneys[1] {
+			minMoneys[1] = price
+		}
+	}
+	if minMoneys[0]+minMoneys[1] > money {
+		return money
+	}
+	return money - minMoneys[0] - minMoneys[1]
+}
diff --git a/leetcode/2735.go b/leetcode/2735.go
new file mode 100644
index 0000000..d861593
--- /dev/null
+++ b/leetcode/2735.go
@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+func minCost(nums []int, x int) int64 {
+	minNums := make([]int, len(nums))
+	copy(minNums, nums)
+	min := func(x int, y int64) int {
+		if int64(x) < y {
+			return x
+		}
+		return int(y)
+	}
+
+	minInt64 := func(x, y int64) int64 {
+		if x < y {
+			return x
+		}
+		return y
+	}
+
+	res := int64(math.MaxInt64)
+
+	for i := 0; i < len(nums); i++ {
+		sum := int64(i * x)
+		for k := 0; k < len(nums); k++ {
+			minNums[k] = min(minNums[k], int64(nums[(k-i+len(nums))%len(nums)]))
+			sum += int64(minNums[k])
+		}
+		res = minInt64(res, sum)
+	}
+	return res
+}
+
+func main() {
+	nums := []int{20, 1, 15}
+	fmt.Println(minCost(nums, 5))
+}
diff --git a/leetcode/2866.go b/leetcode/2866.go
new file mode 100644
index 0000000..ef2051a
--- /dev/null
+++ b/leetcode/2866.go
@@ -0,0 +1,48 @@
+package main
+
+import "fmt"
+
+func maximumSumOfHeights(maxHeights []int) int64 {
+	prefix := make([]int64, len(maxHeights))
+	suffix := make([]int64, len(maxHeights))
+	stack := [][2]int{}
+	for i, height := range maxHeights {
+		for len(stack) > 0 && stack[len(stack)-1][1] > height {
+			stack = stack[:len(stack)-1]
+		}
+		if len(stack) > 0 {
+			lastIdx := stack[len(stack)-1][0]
+			prefix[i] = prefix[lastIdx] + int64(height)*int64(i-lastIdx)
+		} else {
+			prefix[i] = int64(height) * int64(i+1)
+		}
+		stack = append(stack, [2]int{i, height})
+	}
+
+	stack = [][2]int{}
+	for i := len(maxHeights) - 1; i >= 0; i-- {
+		height := maxHeights[i]
+		for len(stack) > 0 && stack[len(stack)-1][1] > height {
+			stack = stack[:len(stack)-1]
+		}
+		if len(stack) > 0 {
+			lastIdx := stack[len(stack)-1][0]
+			suffix[i] = suffix[lastIdx] + int64(height)*int64(lastIdx-i)
+		} else {
+			suffix[i] = int64(height) * int64(len(maxHeights)-i)
+		}
+		stack = append(stack, [2]int{i, height})
+	}
+	res := int64(0)
+	for i := 0; i < len(maxHeights); i++ {
+		if prefix[i]+suffix[i]-int64(maxHeights[i]) > res {
+			res = prefix[i] + suffix[i] - int64(maxHeights[i])
+		}
+	}
+	return res
+}
+
+func main() {
+	nums := []int{5, 3, 4, 1, 1}
+	fmt.Println(maximumSumOfHeights(nums))
+}