In this post, we will solve HackerRank Palindrome Index Problem Solution.
Given a string of lowercase letters in the range ascii[a-z], determine the index of a character that can be removed to make the string a palindrome. There may be more than one solution, but any will do. If the word is already a palindrome or there is no solution, return
-1. Otherwise, return the index of a character to remove.
Example
8 = “bcbc”
Either remove ‘b’ at index 0 or ‘c’ at index 3.
Function Description
Complete the palindromeIndex function in the editor below. palindromelndex has the following parameter(s):
- string s: a string to analyze
Returns - int: the index of the character to remove or -1
Input Format
The first line contains an integer q, the number of queries. Each of the next q lines contains a query string s.
Sample Input
STDIN Function
----- --------
3 q = 3
aaab s = 'aaab' (first query)
baa s = 'baa' (second query)
aaa s = 'aaa' (third query)
Sample Output
3
0
-1Explanation
Query 1: “aaab”
Removing ‘b’ at index 3 results in a palindrome, so return 3.
Query 2: “baa”
Removing ‘b’ at index 0 results in a palindrome, so return 0.
Query 3: “aaa”
This string is already a palindrome, so return -1. Removing any one of the characters would result in a palindrome, but this test comes first.
Palindrome Index C Solution
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
#include <stdbool.h>
void check(char *string, int size) {
int mid = size >>1;
int offendingIndex = -1;
for(int i = 0 ; i < mid; i++) {
if(*(string + i) != *(string +size - 1 -i)) {
offendingIndex = i;
break;
}
}
mid = (size -1) >> 1;
bool isPal = true;
int head = 0;
for(int i = 0 ; i <= mid; i++) {
if(head == offendingIndex) {
++head;
}
if(*(string + head++) != *(string +size - 1 -i)) {
isPal = false;
break;
}
}
if(!isPal) {
offendingIndex = size -1 -offendingIndex;
}
printf("%d\n",offendingIndex);
}
int main() {
/* Enter your code here. Read input from STDIN. Print output to STDOUT */
int T;
scanf("%d", &T);
char *strings[T];
int sizes[T];
for(int i = 0; i < T; i++) {
strings[i] = (char*) malloc(sizeof(char) * 100005 );
scanf("%s", strings[i]);
sizes[i] = strlen(strings[i]);
}
for(int i = 0; i < T; i++) {
check(strings[i], sizes[i]);
}
return 0;
}Palindrome Index C++ Solution
#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
// check if S[i...j] is a palindrome
// returns mismatched index or -1
int check(const std::string& S, int i, int j) {
while (i < j) {
if (S[i] != S[j])
return i;
++i;
--j;
}
return -1;
}
int main() {
int T; std::cin >> T;
for (int t = 0; t < T; ++t) {
std::string S; std::cin >> S;
int mismatch = check(S, 0, S.size()-1);
if (mismatch != -1) {
int i = mismatch;
int j = S.size()-1-i;
// need to remove either i or j
if (check(S, i+1, j) == -1) {
mismatch = i;
} else if (check(S, i, j-1) == -1) {
mismatch = j;
} else {
// no valid solution
mismatch = -1;
}
}
std::cout << mismatch << std::endl;
}
return 0;
}Palindrome Index C Sharp Solution
using System;
using System.Collections.Generic;
using System.IO;
class Solution {
static void Main(String[] args) {
/* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */
int questionCount = Convert.ToInt32(Console.ReadLine());
int[] answers = new int[questionCount];
for (int i = 0; i < questionCount; i++)
{
answers[i] = solve(Console.ReadLine());
}
for (int i = 0; i < questionCount; i++) Console.WriteLine(answers[i]);
}
public static int solve(string s) {
for (int i = 0; i < (s.Length + 1) / 2; i++)
{
int l = i;
int r = s.Length - l - 1;
if (s[l] != s[r]) if (s[l+1] == s[r] && s[l+2] == s[r-1]) return l; else return r;
}
return -1;
}
}Palindrome Index Java Solution
import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;
class Result {
/*
* Complete the 'palindromeIndex' function below.
*
* The function is expected to return an INTEGER.
* The function accepts STRING s as parameter.
*/
public static int palindromeIndex(String s) {
// Write your code here
int l = s.length();
int i,j,a,b;
for (i=0, j=l-1; i<l; i++,j--){
if (s.charAt(i)!=s.charAt(j))
break;
}
if (i>j) return -1;
for (a = i+1, b = j;a<j && b>i+1; a++,b--){
if (s.charAt(a)!=s.charAt(b))
return j;
}
return i;
}
}
public class Solution {
public static void main(String[] args) throws IOException {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
int q = Integer.parseInt(bufferedReader.readLine().trim());
IntStream.range(0, q).forEach(qItr -> {
try {
String s = bufferedReader.readLine();
int result = Result.palindromeIndex(s);
bufferedWriter.write(String.valueOf(result));
bufferedWriter.newLine();
} catch (IOException ex) {
throw new RuntimeException(ex);
}
});
bufferedReader.close();
bufferedWriter.close();
}
}Palindrome Index JavaScript Solution
function processData(input) {
//Enter your code here
var lines = input.split(RegExp("\n", "g"));
var numCases = parseInt(lines[0]);
for(var i = 0; i < numCases; i++){
// Get current line
var str = lines[i+1];
var arr = str.split("");
var found = false;
// Iterate from End and Start
for(var j = 0; j < arr.length/2; j++){
var start = j;
var end = arr.length - 1 - j;
if(arr[start] != arr[end]){
if(arr[start] == arr[end-1] && arr[start+1] == arr[end-2]){
console.log(end);
found = true;
break;
}
else if(arr[start+1] == arr[end]){
console.log(start);
found = true;
break;
}
}
}
if(found == false){
console.log(-1);
}
}
}
process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
_input += input;
});
process.stdin.on("end", function () {
processData(_input);
});Palindrome Index Python Solution
def palindrome(s):
return s == s[::-1]
def palindrome_index(s):
if palindrome(s):
return -1
for c in range(len(s)//2):
if s[c] != s[-(c+1)]:
if palindrome(s[:c]+s[c+1:]):
return c
else:
return len(s)-(c+1)
def main():
test_count = int(input())
for _ in range(test_count):
print(palindrome_index(input()))
main()Other Solution
