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# Bob and Pallindromes CodeChef Solution

## Bob and Pallindromes CodeChef Solution in C++14

#include<bits/stdc++.h>
using namespace std;
#define mod 1000000007

long long power(long long a,int n){
long long ans = 1;

while (n) {
if (n & 1) ans = ((ans % mod) * (a % mod)) % mod;
a = ((a % mod) * (a % mod)) % mod;
n >>= 1;
}

return ans;
}

int solve(int n){
int ans=1;
long long x=power(26,mod-2);
long long y=(2*power(25,mod-2))%mod;
y=(y*(1+mod-power(x,n/2)))%mod;
ans=(ans+y)%mod;
if(n%2==0){
ans=(ans+mod-power(x,n/2))%mod;
}
return ans;
}

int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);

int t, n;

cin >> t;

while (t--) {
cin >> n;
cout << solve(n) << '\n';
}

return 0;
}

## Bob and Pallindromes CodeChef Solution in PYTH 3

import sys

# stdin = open("testdata.txt", "r")
ip = sys.stdin

mod = pow(10, 9) + 7

modinv = lambda x: pow(x, mod-2, mod)

def solve(n):
ans = 1
a = pow(26, n, mod)
d = a
a = (a-1)%mod
a = (a*2)%mod
mmi1 = modinv(d)
mmi2 = modinv(25)
a = (a*mmi1)%mod
a = (a*mmi2)%mod
ans = (a+ ans)%mod
return ans

for _ in range(t):
res = solve(n//2)
if n%2 == 0:
last = modinv(pow(26, n//2, mod))
res = (res - last)%mod
print(res)

## Bob and Pallindromes CodeChef Solution in C

#include <stdio.h>
int mod=(int)1e9+7;
int powmod(int a,int n)
{
int ans=1;
while(n)
{
if(n&1) ans=((long long)ans*a)%mod;
a=((long long)a*a)%mod;
n>>=1;
}
return ans;
}
int main()
{
int i,T,N;
scanf("%d",&T);
for(i=1;i<=T;i++)
{
scanf("%d",&N);
int num,denom;
if(N&1)
{
int temp=powmod(26,(N-1)/2);
denom=((long long)25*temp)%mod;
num=((long long)27*temp)%mod;
num-=2;
if(num<0) num+=mod;
}
else
{
int temp=powmod(26,N/2);
denom=((long long)25*temp)%mod;
temp--;
if(temp==-1) temp=mod-1;
num=((long long)27*temp)%mod;
}
printf("%d\n",((long long)num*powmod(denom,mod-2))%mod);
}
return 0;
}

## Bob and Pallindromes CodeChef Solution in JAVA

/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
/*
Gp formula = 1+2[((1/26)-((1/26^floor(n/2))*(1/26)))/(1-(1/26))] ..... for odd
1+2[((1/26)-((1/26^floor(n/2))*(1/26)))/(1-(1/26))]-(1/26^(n/2)) ..... for Even
*/
class Codechef
{
final static long mod = 1000000007;
public static long power(long number, long pow) {
if(pow==1) {
return number%mod;
}
if(pow==2) {
return (number * number)%mod;
}
long result = power(number,pow/2);
result = (result * result)%mod;
if((pow&1)==1) {
result = (result* number)%mod;
}
return result;
}
public static long solution(int n) {

long r = power(26, mod-2)%mod;

long numeratorTemp = power(26, (long)Math.floor(n/2));

numeratorTemp = power(numeratorTemp, mod-2);

numeratorTemp = (numeratorTemp * r)%mod;

long numerato = ((r - numeratorTemp)+mod)%mod;

long denomenator = ((1 - r)+mod)%mod;

denomenator = power(denomenator, mod-2);

long output = (numerato * denomenator)%mod;

long result1 = (1 + 2 * output)%mod;

if(n%2==0) {

long temp = power(26, n/2);
temp = power(temp, mod-2);
long result2 = ((result1 - temp)+mod)%mod;
return result2;
}else {
return result1;
}
}
public static void main (String[] args) throws java.lang.Exception
{
Scanner sc = new Scanner(System.in);
int t = sc.nextInt();
while(t-->0) {
int n = sc.nextInt();
if(n==1) {
System.out.println(1);;
}else {
System.out.println(solution(n));
}
}
}
}

## Bob and Pallindromes CodeChef Solution in PYTH

mod = 10 ** 9 + 7
inv = lambda x : pow(x, mod-2, mod)
for _ in xrange(int(raw_input())):
n = int(raw_input())
if n == 1 :
print 1
else:
s = 52 * (pow(26, n//2+1, mod) - 1) * inv(pow(26, n//2+1, mod)) * inv(25) - 1
if n % 2  == 0:
s -= inv(pow(26, n//2, mod))
s %= mod
print (s)

## Bob and Pallindromes CodeChef Solution in GO

package main

import (
"bufio"
"bytes"
"fmt"
"os"
)

func main() {

var buf bytes.Buffer
for tc > 0 {
tc--
res := solve(n)
buf.WriteString(fmt.Sprintf("%d\n", res))
}
fmt.Print(buf.String())
}

func readUint64(bytes []byte, from int, val *uint64) int {
i := from

var tmp uint64
for i < len(bytes) && bytes[i] >= '0' && bytes[i] <= '9' {
tmp = tmp*10 + uint64(bytes[i]-'0')
i++
}
*val = tmp

return i
}

func readInt(bytes []byte, from int, val *int) int {
i := from
sign := 1
if bytes[i] == '-' {
sign = -1
i++
}
tmp := 0
for i < len(bytes) && bytes[i] >= '0' && bytes[i] <= '9' {
tmp = tmp*10 + int(bytes[i]-'0')
i++
}
*val = tmp * sign
return i
}

for i := 0; i < len(s); i++ {
if s[i] == '\n' {
return s[:i]
}
}
return s
}

return
}

a, b = res[0], res[1]
return
}

a, b, c = res[0], res[1], res[2]
return
}

res := make([]int, n)
x := 0
for i := 0; i < n; i++ {
for x < len(bs) && (bs[x] < '0' || bs[x] > '9') && bs[x] != '-' {
x++
}
}
return res
}

const MOD = 1000000007

func pow(a, b int) int64 {
A := int64(a)
R := int64(1)
for b > 0 {
if b&1 == 1 {
R = (R * A) % MOD
}
A = (A * A) % MOD
b >>= 1
}
return R
}

func solve(n int) int {
var f int
if n&1 == 0 {
f = 1
}
last := pow(26, n/2)
last = pow(int(last), MOD-2)

n -= f

a := pow(26, n/2)
d := a
a = (a - 1 + MOD) % MOD
a = (a * 2) % MOD
mmi1 := pow(int(d), MOD-2)
mmi2 := pow(25, MOD-2)
a = (a * mmi1) % MOD
a = (a * mmi2) % MOD
ans := (a + 1) % MOD
if f == 1 {
ans = (ans + last) % MOD
}
return int(ans)
}
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