Long palin sub

challenges/intermediate/longest-palindromic-substring/long-palin.py

@@ -0,0 +1,41 @@
+def find_long_palin_substr(string: str) -> str:
+	max_length: int = 1
+
+	start = 0
+	length = len(string)
+	max_even_substr, max_odd_substr = string[0], string[0]
+
+	for i in range(1, length):
+		# use i as index center for even subs
+		even_substr, start, max_length = find_palin_substr(string, start, length, max_length, low=(i-1), high=i)
+
+		# use i as index center for odd subs
+		odd_substr, start, max_length = find_palin_substr(string, start, length, max_length, low=(i-1), high=(i+1))
+
+		if len(even_substr) > len(max_even_substr):
+			max_even_substr = even_substr
+		if len(odd_substr) > len(max_odd_substr):
+			max_odd_substr = odd_substr
+
+	return max_even_substr if len(max_even_substr) >= len(max_odd_substr) else max_odd_substr
+
+
+def find_palin_substr(string: str, start: int, length: int, max_length: int, low: int, high: int) -> tuple:
+
+	while low >= 0 and high < length and string[low] == string[high]:
+		low -= 1
+		high += 1
+
+	low += 1
+	high -= 1
+	if (string[low] == string[high]) and ((high - low + 1) > max_length):
+		start = low
+		max_length = high - low + 1
+
+	return string[start:start + max_length], start, max_length
+
+
+if __name__ == "__main__":
+	stringList = ["babad", "cbbd", "a", "ac"]
+	for s in stringList:
+		print("String:\t{}\nPalindromic substring:\t{}\n".format(s, find_long_palin_substr(s)))

challenges/intermediate/longest-palindromic-substring/long-palin.ts

@@ -0,0 +1,58 @@
+function find_palin_substr (string: string, start: number, low: number, high: number, length: number, max_length: number) {
+    while (low >= 0 && high < length && (string[low] === string[high])) {
+        low -= 1;
+		high += 1;
+    }
+
+    low += 1;
+	high -= 1;
+
+    if ((string[low] === string[high]) && ((high - low + 1) > max_length)) {
+        start = low;
+		max_length = high - low + 1;
+    }
+
+    return [string.slice(start, start + max_length), start, max_length]
+}
+
+function find_long_palin_substr (string: string) {
+
+    let max_length: number = 1;
+    let start: number = 0;
+    let length: number = string.length;
+	let max_even_substr: string = string[0];
+    let max_odd_substr: string = string[0];
+    let even_substr: string;
+    let odd_substr: string;
+    let find_palin_return = [];
+
+    for (let i = 1; i < length; i++) {
+        // use i as index center for even subs
+		find_palin_return = find_palin_substr(string, start, i-1, i, length, max_length);
+        even_substr = find_palin_return[0].toString();
+        start = Number(find_palin_return[1]);
+        max_length = Number(find_palin_return[2]);
+
+        // use i as index center for odd subs
+        find_palin_return = find_palin_substr(string, start, i-1, i+1, length, max_length);
+        odd_substr = find_palin_return[0].toString();
+        start = Number(find_palin_return[1]);
+        max_length = Number(find_palin_return[2]);
+
+        if (even_substr.length > max_even_substr.length) {
+            max_even_substr = even_substr
+        }
+        if (odd_substr.length > max_odd_substr.length) {
+            max_odd_substr = odd_substr
+        } 
+    }
+
+    if (max_even_substr.length > max_odd_substr.length) {
+        return max_even_substr
+    } else return max_odd_substr
+}
+
+console.log(find_long_palin_substr("cbbd"));
+console.log(find_long_palin_substr("babad"));
+console.log(find_long_palin_substr("a"));
+console.log(find_long_palin_substr("ac"));