restructure solutions dir

solutions/1/q125/solution.go

@@ -0,0 +1,32 @@
+package q125
+
+func isAlphanumeric(c byte) bool {
+	return c >= '0' && c <= '9' ||
+		c >= 'a' && c <= 'z'
+}
+
+func toLower(c byte) byte {
+	if c >= 'A' && c <= 'Z' {
+		return 'a' + c - 'A'
+	}
+	return c
+}
+
+func isPalindrome(s string) bool {
+	conv := make([]byte, 0, len(s))
+	for i := range len(s) {
+		c := toLower(s[i])
+		if isAlphanumeric(c) {
+			conv = append(conv, c)
+		}
+	}
+
+	for i := range len(conv) / 2 {
+		if conv[i] != conv[len(conv)-1-i] {
+			return false
+		}
+	}
+	return true
+}
+
+var _ = isPalindrome

solutions/1/q134/solution.go

@@ -0,0 +1,23 @@
+package q134
+
+func canCompleteCircuit(gas []int, cost []int) int {
+	invalidated := 0
+	start, current, tank := 0, 0, 0
+
+	for {
+		tank = tank + gas[current] - cost[current]
+		current = (current + 1) % len(gas)
+		if tank < 0 {
+			invalidated += (current - start + len(gas)) % len(gas)
+			if invalidated >= len(gas) || current == start {
+				return -1
+			}
+			start = current
+			tank = 0
+		} else if current == start {
+			return start
+		}
+	}
+}
+
+var _ = canCompleteCircuit

solutions/1/q134/solution_test.go

@@ -0,0 +1,34 @@
+package q134
+
+import (
+	"testing"
+)
+
+func Test_canCompleteCircuit(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		gas  []int
+		cost []int
+		want int
+	}{
+		{
+			gas:  []int{1, 2, 3, 4, 5},
+			cost: []int{3, 4, 5, 1, 2},
+			want: 3,
+		},
+		{
+			gas:  []int{2, 3, 4},
+			cost: []int{3, 4, 3},
+			want: -1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := canCompleteCircuit(tt.gas, tt.cost)
+			if got != tt.want {
+				t.Errorf("canCompleteCircuit() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

solutions/1/q135/solution.go

@@ -0,0 +1,26 @@
+package q135
+
+func candy(ratings []int) int {
+	n := len(ratings)
+	candies := make([]int, n)
+
+	for i := range n {
+		candies[i] = 1
+		if i > 0 && ratings[i-1] < ratings[i] {
+			candies[i] = candies[i-1] + 1
+		}
+	}
+	for i := n - 2; i >= 0; i-- {
+		if ratings[i+1] < ratings[i] {
+			candies[i] = max(candies[i], candies[i+1]+1)
+		}
+	}
+
+	sum := 0
+	for _, c := range candies {
+		sum += c
+	}
+	return sum
+}
+
+var _ = candy

solutions/1/q150/solution.go

@@ -0,0 +1,24 @@
+package q150
+
+func twoSum(numbers []int, target int) []int {
+	l, r := 0, len(numbers)-1
+
+	for l < r {
+		for numbers[r]+numbers[l] > target {
+			r--
+		}
+		if numbers[r]+numbers[l] == target {
+			return []int{l + 1, r + 1}
+		}
+
+		for numbers[r]+numbers[l] < target {
+			l++
+		}
+		if numbers[r]+numbers[l] == target {
+			return []int{l + 1, r + 1}
+		}
+	}
+	return []int{} // impossible
+}
+
+var _ = twoSum