Add problem 647 - Palindromic Substrings

Author: anirudhology

problems/dynamic_programming/palindromic_substrings.go

@@ -0,0 +1,29 @@
+package dynamic_programming
+
+func PalindromicSubstrings(s string) int {
+	// Special case
+	if len(s) == 0 {
+		return 0
+	}
+	// Count to store total number of palindromic substrings
+	count := 0
+	// Process each string by keeping each index as middle and
+	// expand both sides from it
+	for i := 0; i < len(s); i++ {
+		// Odd length
+		count += expandFromCenterForPalindromicSubstrings(s, i, i)
+		// Even length
+		count += expandFromCenterForPalindromicSubstrings(s, i, i+1)
+	}
+	return count
+}
+
+func expandFromCenterForPalindromicSubstrings(s string, left int, right int) int {
+	count := 0
+	for left >= 0 && right < len(s) && s[left] == s[right] {
+		left--
+		right++
+		count++
+	}
+	return count
+}

tests/dynamic_programming/palindromic_substrings_test.go

@@ -0,0 +1,34 @@
+package dynamic_programming_test
+
+import (
+	"testing"
+
+	"github.com/anirudhology/leetcode-go/problems/dynamic_programming"
+)
+
+func TestPalindromicSubstrings(t *testing.T) {
+	// Test case for null string
+	if result := dynamic_programming.PalindromicSubstrings(""); result != 0 {
+		t.Errorf("Expected 0, got %d", result)
+	}
+
+	// Test case for single character string
+	if result := dynamic_programming.PalindromicSubstrings("a"); result != 1 {
+		t.Errorf("Expected 1, got %d", result)
+	}
+
+	// Test case for string with all same characters
+	if result := dynamic_programming.PalindromicSubstrings("aaaa"); result != 10 {
+		t.Errorf("Expected 10, got %d", result)
+	}
+
+	// Test case for string with mixed characters
+	if result := dynamic_programming.PalindromicSubstrings("abc"); result != 3 {
+		t.Errorf("Expected 3, got %d", result)
+	}
+
+	// Test case for string with palindromic substrings
+	if result := dynamic_programming.PalindromicSubstrings("aaa"); result != 6 {
+		t.Errorf("Expected 6, got %d", result)
+	}
+}