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# PRPALIN - Editorial

Practice

Editorialist: SUSHANT AGARWAL

SIMPLE

# PREREQUISITES:

Basic looping,Conditional statements

# PROBLEM:

You will be given an integer N, 1 ≤ N ≤ 1000000. You must find the smallest integer M ≥ N such that M is a prime number and M is a palindrome.

# EXPLANATION:

Check every odd number after N (using a loop) for 2 properties

1)It should be prime 2) The number should be equal to its reverse.

Print the first number that satisfies these 2 properties and then break out of the loop when this number is encountered.

# EDITORIALIST'S SOLUTION:

Editorialist's solution can be found here.

This question is marked "community wiki".

21368
accept rate: 0%

19.8k350498541

1

Nice job, but please format your code if you want someone to be able to understand it easily - use for example this - http://prettyprinter.de/index.php

...after N...

is not correct, M >= N right?

(18 Dec '14, 17:45)

# include<math.h>

int check(int num) { int rev_num = 0; while(num > 0) { rev_num = rev_num*10 + num%10; num = num/10; } return rev_num; } int main() { int n,i; scanf("%d",&n); if(n==1) { printf("2\n"); } else if(n==2) printf("3\n"); else{ if(n%2==0) n++; else n=n+2; do{ int x=sqrt(n); for(i=3;i<=x;i++) { if(n%i==0) break; } if(n%i!=0) { int j=check(n); if(j==n) { printf("%d\n",n); break; } } n=n+2; }while(1); } return 0; } why this not work

4★grb47
1
accept rate: 0%

Do not post questions like this as an answer.

(14 Feb '15, 13:33) 1★
 0 The solution given in this editorial is wrong. For the input of 10010 it gives output 10201 but rather it should be 10301 answered 21 Feb '15, 07:13 1★lincoln 1 accept rate: 0%
 0 answer is right..10201 is smaller than 10301 answered 17 Apr '15, 01:07 25●1●1●4 accept rate: 0%
 0 why my solution is going for tle,.. http://www.codechef.com/viewsolution/6782096 answered 17 Apr '15, 01:17 25●1●1●4 accept rate: 0%
 0 10201 is divisible by 101 hence it is not a prime no Hence the awnser for 10010 is 10301 answered 25 Sep '15, 22:14 1 accept rate: 0%
 0 10201 is divisible by 101 hence it is not a prime no Hence the answer for 10010 is 10301 answered 25 Sep '15, 22:14 1 accept rate: 0%
 0 sir i have applied seive of atkins to found prime but still getting tle answered 20 Feb '16, 22:20 16 accept rate: 33%
 0 have u submitted it or checking it in codechef IDE? answered 20 Feb '16, 22:37 11●2 accept rate: 0%
 0 Serious issue - Editorialist's solution is wrong as output for 10000 is 10201 which is 101^2. This also means that the testcases are weak. answered 21 Jan, 19:26 9●1 accept rate: 0%
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question asked: 18 Dec '14, 16:56

question was seen: 5,956 times

last updated: 21 Jan, 19:28