add logest-palindromic-subsequence

Author: freefcw

go/longest-palindromic-subsequence.go

@@ -0,0 +1,40 @@
+package leetcode
+
+// https://leetcode.com/problems/longest-palindromic-subsequence/
+
+func longestPalindromeSubseq(s string) int {
+	length := len(s)
+	if length == 0 {
+		return 0
+	}
+	dp := make([][]int, length)
+	for i := 0; i < length; i++ {
+		dp[i] = make([]int, length)
+	}
+
+	for i := 0; i < length; i++ {
+		for j := 0; j < length-i; j++ {
+			k := i + j
+			dp[j][k] = 1
+			if j == k {
+				continue
+			}
+			if i == 1 && s[j] == s[k] {
+				dp[j][j+1] = 2
+				continue
+			}
+			max := dp[j][k-1]
+			if max < dp[j+1][k] {
+				max = dp[j+1][k]
+			}
+			if s[j] == s[k] {
+				max = dp[j+1][k-1] + 2
+			}
+			dp[j][k] = max
+		}
+	}
+	// for _, item := range dp {
+	// 	fmt.Println(item)
+	// }
+	return dp[0][length-1]
+}

go/longest-palindromic-subsequence_test.go

@@ -0,0 +1,40 @@
+package leetcode
+
+import "testing"
+
+func TestLongestPalindromeSubseq(t *testing.T) {
+	tests := []struct {
+		input  string
+		expect int
+	}{
+		{
+			input:  "bbbab",
+			expect: 4,
+		}, {
+			input:  "cbbd",
+			expect: 2,
+		}, {
+			input:  "abcabcba",
+			expect: 7,
+		}, {
+			input:  "",
+			expect: 0,
+		}, {
+			input:  "a",
+			expect: 1,
+		}, {
+			input:  "aa",
+			expect: 2,
+		}, {
+			input:  "euazbipzncptldueeuechubrcourfpftcebikrxhybkymimgvldiwqvkszfycvqyvtiwfckexmowcxztkfyzqovbtmzpxojfofbvwnncajvrvdbvjhcrameamcfmcoxryjukhpljwszknhiypvyskmsujkuggpztltpgoczafmfelahqwjbhxtjmebnymdyxoeodqmvkxittxjnlltmoobsgzdfhismogqfpfhvqnxeuosjqqalvwhsidgiavcatjjgeztrjuoixxxoznklcxolgpuktirmduxdywwlbikaqkqajzbsjvdgjcnbtfksqhquiwnwflkldgdrqrnwmshdpykicozfowmumzeuznolmgjlltypyufpzjpuvucmesnnrwppheizkapovoloneaxpfinaontwtdqsdvzmqlgkdxlbeguackbdkftzbnynmcejtwudocemcfnuzbttcoew",
+			expect: 159,
+		},
+	}
+
+	for _, item := range tests {
+		actual := longestPalindromeSubseq(item.input)
+		if actual != item.expect {
+			t.Fatalf("%s expect %d, actual %d\n", item.input, item.expect, actual)
+		}
+	}
+}