A: Longest Valid Parentheses

Author: Shuo

internal/leetcode/problems_status.go

@@ -27,6 +27,7 @@ var problemStatus = map[int]bool{
 	26:   true,
 	27:   true,
 	28:   true,
+	32:   true,
 	35:   true,
 	36:   true,
 	38:   true,

problems/longest-valid-parentheses/longest_valid_parentheses.go

@@ -1 +1,26 @@
 package problem32
+
+func longestValidParentheses(s string) int {
+	ans, l := 0, len(s)
+	dp := make([]int, l)
+	for i, c := range s {
+		if i == 0 || c == '(' {
+			continue
+		}
+		if s[i-1] == '(' {
+			dp[i] = 2
+			if i > 1 {
+				dp[i] = dp[i-2] + 2
+			}
+		} else if i > dp[i-1] && s[i-1-dp[i-1]] == '(' {
+			dp[i] = dp[i-1] + 2
+			if i-1 > dp[i-1] {
+				dp[i] += dp[i-2-dp[i-1]]
+			}
+		}
+		if dp[i] > ans {
+			ans = dp[i]
+		}
+	}
+	return ans
+}

problems/longest-valid-parentheses/longest_valid_parentheses_test.go

@@ -1 +1,35 @@
 package problem32
+
+import "testing"
+
+type testType struct {
+	in   string
+	want int
+}
+
+func TestLongestValidParentheses(t *testing.T) {
+	tests := [...]testType{
+		{
+			in:   "(()",
+			want: 2,
+		},
+		{
+			in:   ")()())",
+			want: 4,
+		},
+		{
+			in:   ")()())(())()(",
+			want: 6,
+		},
+		{
+			in:   "()(())",
+			want: 6,
+		},
+	}
+	for _, tt := range tests {
+		got := longestValidParentheses(tt.in)
+		if got != tt.want {
+			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
+		}
+	}
+}