From 0f5f9e331ca8c04358d4156da99933e856dab38e Mon Sep 17 00:00:00 2001
From: Yiyang Kang <kkyy@kkyy.me>
Date: Tue, 17 Feb 2026 14:25:55 +0900
Subject: [PATCH] add new solutions

---
 .sqlfluff                      |  5 ++
 solutions/0/q43/solution.go    | 49 +++++++++++++++++++
 solutions/0/q68/solution.go    | 63 ++++++++++++++++++++++++
 solutions/0/q8/solution.go     | 56 ++++++++++++++++++++++
 solutions/10/q1041/solution.go | 40 ++++++++++++++++
 solutions/3/q399/solution.go   | 60 +++++++++++++++++++++++
 solutions/37/q3713/solution.go | 35 ++++++++++++++
 solutions/37/q3714/solution.go | 88 ++++++++++++++++++++++++++++++++++
 solutions/37/q3719/solution.go | 53 ++++++++++++++++++++
 solutions/4/q401/solution.go   | 45 +++++++++++++++++
 solutions/4/q445/solution.go   | 45 +++++++++++++++++
 11 files changed, 539 insertions(+)
 create mode 100644 .sqlfluff
 create mode 100644 solutions/0/q43/solution.go
 create mode 100644 solutions/0/q68/solution.go
 create mode 100644 solutions/0/q8/solution.go
 create mode 100644 solutions/10/q1041/solution.go
 create mode 100644 solutions/3/q399/solution.go
 create mode 100644 solutions/37/q3713/solution.go
 create mode 100644 solutions/37/q3714/solution.go
 create mode 100644 solutions/37/q3719/solution.go
 create mode 100644 solutions/4/q401/solution.go
 create mode 100644 solutions/4/q445/solution.go

diff --git a/.sqlfluff b/.sqlfluff
new file mode 100644
index 0000000..9915309
--- /dev/null
+++ b/.sqlfluff
@@ -0,0 +1,5 @@
+[sqlfluff]
+dialect = mysql
+exclude_rules = CP02, AM04
+
+# vim: ft=toml
diff --git a/solutions/0/q43/solution.go b/solutions/0/q43/solution.go
new file mode 100644
index 0000000..bbb1b48
--- /dev/null
+++ b/solutions/0/q43/solution.go
@@ -0,0 +1,49 @@
+package q43
+
+import "slices"
+
+func multiply(num1, num2 string) string {
+	if num1 == "0" || num2 == "0" {
+		return "0"
+	}
+
+	l1, l2 := len(num1), len(num2)
+	res := make([]byte, l1+l2)
+
+	// Calculation
+	for i1 := range l1 {
+		n1 := num1[l1-1-i1] - '0'
+		if n1 == 0 {
+			continue
+		}
+		for i2 := range l2 {
+			n2 := num2[l2-1-i2] - '0'
+			j := i1 + i2
+			res[j] += n1 * n2
+			if res[j] > 9 {
+				res[j+1] += res[j] / 10
+				res[j] = res[j] % 10
+			}
+		}
+		for i := l2 + i1; res[i] > 9; i++ {
+			res[i+1] += res[i] / 10
+			res[i] = res[i] % 10
+		}
+	}
+
+	// Post process
+	for i := len(res) - 1; i >= 0; i-- {
+		if res[i] > 0 {
+			res = res[:i+1]
+			break
+		}
+	}
+
+	slices.Reverse(res)
+	for i := range res {
+		res[i] = res[i] + '0'
+	}
+	return string(res)
+}
+
+var _ = multiply
diff --git a/solutions/0/q68/solution.go b/solutions/0/q68/solution.go
new file mode 100644
index 0000000..d536aa9
--- /dev/null
+++ b/solutions/0/q68/solution.go
@@ -0,0 +1,63 @@
+package q68
+
+var (
+	emptyLine = make([]byte, 100)
+	buf       = make([]byte, 100)
+)
+
+func init() {
+	for i := range emptyLine {
+		emptyLine[i] = ' '
+	}
+}
+
+func emitLine(line []byte, words []string, justifyLeft bool) string {
+	spaces := len(line)
+	for i := range words {
+		spaces -= len(words[i])
+	}
+	lenSep := spaces / max(len(words)-1, 1)
+	leftover := spaces % max(len(words)-1, 1)
+
+	offset := len(words[0])
+	copy(line, words[0])
+	for i := 1; i < len(words); i++ {
+		var spaces = 1
+		if !justifyLeft {
+			spaces = lenSep
+			if i <= leftover {
+				spaces++
+			}
+		}
+		offset += spaces
+		copy(line[offset:], words[i])
+		offset += len(words[i])
+	}
+	return string(line)
+}
+
+func fullJustify(words []string, maxWidth int) []string {
+	ret := []string{}
+	line := buf[:maxWidth]
+	copy(line, emptyLine)
+
+	i := 0
+	lineLen := len(words[0])
+	for j := 1; j < len(words); j++ {
+		if lineLen+1+len(words[j]) <= maxWidth {
+			lineLen += 1 + len(words[j])
+			continue
+		}
+
+		ret = append(ret, emitLine(line, words[i:j], false))
+		copy(line, emptyLine)
+
+		i = j
+		lineLen = len(words[j])
+	}
+
+	// Last line
+	return append(ret, emitLine(line, words[i:], true))
+}
+
+var _ = fullJustify
diff --git a/solutions/0/q8/solution.go b/solutions/0/q8/solution.go
new file mode 100644
index 0000000..8698445
--- /dev/null
+++ b/solutions/0/q8/solution.go
@@ -0,0 +1,56 @@
+package q8
+
+const (
+	MIN = -(1 << 31)
+	MAX = 1<<31 - 1
+)
+
+func myAtoi(s string) int {
+	sign := 0
+	num := 0
+
+Loop:
+	for i := range len(s) {
+		c := s[i]
+
+		switch c {
+		case '-':
+			if sign != 0 {
+				break Loop
+			}
+			sign = -1
+
+		case '+':
+			if sign != 0 {
+				break Loop
+			}
+			sign = 1
+
+		case ' ':
+			if sign != 0 {
+				break Loop
+			}
+
+		default:
+			if c < '0' || c > '9' {
+				break Loop
+			}
+			if sign == 0 {
+				sign = 1
+			}
+			num = num*10 + int(c-'0')
+			if sign*num < MIN {
+				num = -MIN
+				break Loop
+			}
+			if sign*num > MAX {
+				num = MAX
+				break Loop
+			}
+		}
+	}
+
+	return sign * num
+}
+
+var _ = myAtoi
diff --git a/solutions/10/q1041/solution.go b/solutions/10/q1041/solution.go
new file mode 100644
index 0000000..4aa06fe
--- /dev/null
+++ b/solutions/10/q1041/solution.go
@@ -0,0 +1,40 @@
+package q1041
+
+type Dir int8
+
+const (
+	UP Dir = iota
+	RIGHT
+	DOWN
+	LEFT
+)
+
+func (d Dir) TurnL() Dir { return (d + 3) % 4 }
+func (d Dir) TurnR() Dir { return (d + 1) % 4 }
+
+var vects = [][2]int{{0, -1}, {1, 0}, {0, 1}, {-1, 0}}
+
+func isRobotBounded(instructions string) bool {
+	x, y, d := 0, 0, UP
+
+	for range 4 {
+		for i := range len(instructions) {
+			switch instructions[i] {
+			case 'G':
+				x += vects[d][0]
+				y += vects[d][1]
+			case 'L':
+				d = d.TurnL()
+			case 'R':
+				d = d.TurnR()
+			}
+		}
+
+		if x == 0 && y == 0 && d == UP {
+			return true
+		}
+	}
+	return false
+}
+
+var _ = isRobotBounded
diff --git a/solutions/3/q399/solution.go b/solutions/3/q399/solution.go
new file mode 100644
index 0000000..bc909ba
--- /dev/null
+++ b/solutions/3/q399/solution.go
@@ -0,0 +1,60 @@
+package q399
+
+func calcEquation(equations [][]string, values []float64, queries [][]string) []float64 {
+	seen := make(map[[2]string]float64, len(equations)*8)
+	queue := make([][2]string, 0, len(equations)*8)
+
+	for i := range equations {
+		eq, val := equations[i], values[i]
+		eq1, eq2 := [2]string{eq[0], eq[1]}, [2]string{eq[1], eq[0]}
+		seen[eq1] = val
+		seen[eq2] = 1 / val
+		queue = append(queue, eq1, eq2)
+
+		seen[[2]string{eq[0], eq[0]}] = 1
+		seen[[2]string{eq[1], eq[1]}] = 1
+	}
+
+	for ; len(queue) > 0; queue = queue[1:] {
+		eq := queue[0]
+		val := seen[eq]
+
+		for i := range equations {
+			var newVar string
+			newVal := val
+			switch eq[0] {
+			case equations[i][0]:
+				newVar = equations[i][1]
+				newVal *= 1 / values[i]
+			case equations[i][1]:
+				newVar = equations[i][0]
+				newVal *= values[i]
+			default:
+				continue
+			}
+
+			newEq1 := [2]string{newVar, eq[1]}
+			if _, ok := seen[newEq1]; !ok {
+				seen[newEq1] = newVal
+				queue = append(queue, newEq1)
+			}
+			newEq2 := [2]string{eq[1], newVar}
+			if _, ok := seen[newEq2]; !ok {
+				seen[newEq2] = 1 / newVal
+				queue = append(queue, newEq2)
+			}
+		}
+	}
+
+	ret := make([]float64, len(queries))
+	for i := range queries {
+		if val, ok := seen[[2]string{queries[i][0], queries[i][1]}]; ok {
+			ret[i] = val
+		} else {
+			ret[i] = -1
+		}
+	}
+	return ret
+}
+
+var _ = calcEquation
diff --git a/solutions/37/q3713/solution.go b/solutions/37/q3713/solution.go
new file mode 100644
index 0000000..19f429f
--- /dev/null
+++ b/solutions/37/q3713/solution.go
@@ -0,0 +1,35 @@
+package q3713
+
+func longestBalanced(s string) int {
+	longest := 0
+	cnt, tmp := [26]int{}, [26]int{}
+
+	for i := range len(s) {
+		copy(cnt[:], tmp[:])
+		distinct, imbal, maxCnt := 0, 0, 0
+
+		for j := i; j >= 0; j-- {
+			c := s[j] - 'a'
+			cnt[c]++
+			if cnt[c] == 1 {
+				distinct++
+				imbal++
+			}
+
+			if cnt[c] > maxCnt {
+				maxCnt = cnt[c]
+				imbal = distinct - 1
+			} else if cnt[c] == maxCnt {
+				imbal--
+			}
+
+			if imbal == 0 {
+				longest = max(longest, i-j+1)
+			}
+		}
+	}
+
+	return longest
+}
+
+var _ = longestBalanced
diff --git a/solutions/37/q3714/solution.go b/solutions/37/q3714/solution.go
new file mode 100644
index 0000000..7825100
--- /dev/null
+++ b/solutions/37/q3714/solution.go
@@ -0,0 +1,88 @@
+package q3714
+
+func longestBalanced(s string) int {
+	longest := 0
+	single := 0
+	diff3 := make(map[[2]int]int, len(s))
+	diffAB, diffAC := 0, 0
+
+	diff2AB, diff2AC, diff2BC := map[int]int{}, map[int]int{}, map[int]int{}
+	nDiff2AB, nDiff2AC, nDiff2BC := 0, 0, 0
+	lastA, lastB, lastC := -1, -1, -1
+
+	for i := range len(s) {
+		// Single
+		if i > 0 && s[i] == s[i-1] {
+			single++
+		} else {
+			single = 1
+		}
+		longest = max(longest, single)
+
+		// Dual
+		var process2pair = func(diffIdx map[int]int, offset, i, diff int) int {
+			if diff == 0 {
+				return i - offset
+			}
+			if prev, ok := diffIdx[diff]; !ok {
+				diffIdx[diff] = i
+				return 0
+			} else {
+				return i - prev
+			}
+		}
+		switch s[i] {
+		case 'a':
+			lastA = i
+			nDiff2BC, diff2BC = 0, map[int]int{}
+			nDiff2AB++
+			nDiff2AC++
+			t1 := process2pair(diff2AB, lastC, i, nDiff2AB)
+			t2 := process2pair(diff2AC, lastB, i, nDiff2AC)
+			longest = max(longest, t1, t2)
+
+		case 'b':
+			lastB = i
+			nDiff2AC, diff2AC = 0, map[int]int{}
+			nDiff2AB--
+			nDiff2BC++
+			t1 := process2pair(diff2AB, lastC, i, nDiff2AB)
+			t2 := process2pair(diff2BC, lastA, i, nDiff2BC)
+			longest = max(longest, t1, t2)
+
+		case 'c':
+			lastC = i
+			nDiff2AB, diff2AB = 0, map[int]int{}
+			nDiff2BC--
+			nDiff2AC--
+			t1 := process2pair(diff2BC, lastA, i, nDiff2BC)
+			t2 := process2pair(diff2AC, lastB, i, nDiff2AC)
+			longest = max(longest, t1, t2)
+		}
+
+		// Triple
+		switch s[i] {
+		case 'a':
+			diffAB++
+			diffAC++
+		case 'b':
+			diffAB--
+		case 'c':
+			diffAC--
+		}
+		key := [2]int{diffAB, diffAC}
+		if key == [2]int{0, 0} {
+			longest = i + 1
+			continue
+		}
+		if prev, ok := diff3[key]; !ok {
+			diff3[key] = i
+		} else {
+			longest = max(longest, i-prev)
+		}
+	}
+
+	return longest
+}
+
+var _ = longestBalanced
diff --git a/solutions/37/q3719/solution.go b/solutions/37/q3719/solution.go
new file mode 100644
index 0000000..4a6f3e7
--- /dev/null
+++ b/solutions/37/q3719/solution.go
@@ -0,0 +1,53 @@
+package q3719
+
+var seen [6000]bool
+
+func longestBalanced(nums []int) int {
+	// Map numbers to reduce the range
+	mapped := make(map[int]int, len(nums))
+	nextEven, nextOdd := 0, 1
+	for i := range nums {
+		if m, ok := mapped[nums[i]]; ok {
+			nums[i] = m
+		} else if nums[i]%2 == 0 {
+			mapped[nums[i]] = nextEven
+			nums[i] = nextEven
+			nextEven += 2
+		} else {
+			mapped[nums[i]] = nextOdd
+			nums[i] = nextOdd
+			nextOdd += 2
+		}
+	}
+	numRange := max(nextEven, nextOdd)
+	copy(seen[:3000], seen[3000:]) // init
+
+	longest := 0
+	for i := 1; i < len(nums); i++ {
+		copy(seen[:numRange], seen[numRange:]) // reset
+		odd, even := 0, 0
+		for j := i; j >= 0; j-- {
+			num := nums[j]
+			if seen[num] {
+				if even == odd {
+					longest = max(longest, i-j+1)
+				}
+				continue
+			}
+			seen[num] = true
+
+			if num%2 == 0 {
+				even++
+			} else {
+				odd++
+			}
+			if even == odd {
+				longest = max(longest, i-j+1)
+			}
+		}
+	}
+
+	return longest
+}
+
+var _ = longestBalanced
diff --git a/solutions/4/q401/solution.go b/solutions/4/q401/solution.go
new file mode 100644
index 0000000..2361179
--- /dev/null
+++ b/solutions/4/q401/solution.go
@@ -0,0 +1,45 @@
+package q401
+
+import "fmt"
+
+func bin2time(leds []uint8) (string, bool) {
+	hour := leds[0]<<3 + leds[1]<<2 + leds[2]<<1 + leds[3]
+	minute := leds[4]<<5 +
+		leds[5]<<4 +
+		leds[6]<<3 +
+		leds[7]<<2 +
+		leds[8]<<1 +
+		leds[9]
+	if hour >= 12 || minute >= 60 {
+		return "", false
+	}
+	return fmt.Sprintf("%d:%02d", hour, minute), true
+}
+
+func iterate(remaining, offset int, leds []uint8, ret *[]string) {
+	if 10-offset < remaining {
+		return
+	}
+	if remaining == 0 {
+		if r, ok := bin2time(leds); ok {
+			*ret = append(*ret, r)
+		}
+		return
+	}
+
+	leds[offset] = 1
+	iterate(remaining-1, offset+1, leds, ret)
+	leds[offset] = 0
+	iterate(remaining, offset+1, leds, ret)
+}
+
+func readBinaryWatch(turnedOn int) []string {
+	if turnedOn >= 9 {
+		return nil
+	}
+	ret := []string{}
+	iterate(turnedOn, 0, make([]uint8, 10), &ret)
+	return ret
+}
+
+var _ = readBinaryWatch
diff --git a/solutions/4/q445/solution.go b/solutions/4/q445/solution.go
new file mode 100644
index 0000000..6e697c1
--- /dev/null
+++ b/solutions/4/q445/solution.go
@@ -0,0 +1,45 @@
+package q445
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
+	var a1, a2 []*ListNode
+	for l1 != nil {
+		a1 = append(a1, l1)
+		l1 = l1.Next
+	}
+	for l2 != nil {
+		a2 = append(a2, l2)
+		l2 = l2.Next
+	}
+
+	ret := make([]ListNode, max(len(a1), len(a2))+1)
+	for i := range ret {
+		if i < len(a1) {
+			ret[i].Val += a1[len(a1)-1-i].Val
+		}
+		if i < len(a2) {
+			ret[i].Val += a2[len(a2)-1-i].Val
+		}
+		if ret[i].Val > 9 {
+			ret[i+1].Val += ret[i].Val / 10
+			ret[i].Val %= 10
+		}
+
+		if i > 0 {
+			ret[i].Next = &ret[i-1]
+		}
+	}
+
+	for i := len(ret) - 1; i >= 0; i-- {
+		if ret[i].Val > 0 {
+			return &ret[i]
+		}
+	}
+	return &ret[0]
+}
+
+var _ = addTwoNumbers