Add: 132 Pattern

Author: openset

problems/132-pattern/132_pattern.go

@@ -1 +1,16 @@
 package p_132_pattern
+
+func find132pattern(nums []int) bool {
+	ak, ajStack := -1<<31, make([]int, 0, len(nums))
+	for i := len(nums) - 1; 0 <= i; i-- {
+		if nums[i] < ak {
+			return true
+		}
+		for len(ajStack) > 0 && ajStack[len(ajStack)-1] < nums[i] {
+			ak = ajStack[len(ajStack)-1]
+			ajStack = ajStack[:len(ajStack)-1]
+		}
+		ajStack = append(ajStack, nums[i])
+	}
+	return false
+}

problems/132-pattern/132_pattern_test.go

@@ -1 +1,31 @@
 package p_132_pattern
+
+import "testing"
+
+type caseType struct {
+	input    []int
+	expected bool
+}
+
+func TestFind132pattern(t *testing.T) {
+	tests := [...]caseType{
+		{
+			input:    []int{1, 2, 3, 4},
+			expected: false,
+		},
+		{
+			input:    []int{3, 1, 4, 2},
+			expected: true,
+		},
+		{
+			input:    []int{-1, 3, 2, 0},
+			expected: true,
+		},
+	}
+	for _, tc := range tests {
+		output := find132pattern(tc.input)
+		if output != tc.expected {
+			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
+		}
+	}
+}