8630. Maximum digit in a number

Find the maximum digit in a positive integer n.

Input. One positive integer n (n < 1018).

Output. Print the maximum digit in the positive integer n.

Sample input	Sample output
2354	5

SOLUTION

loop

Algorithm analysis

Divide the number n by 10 until the result becomes zero. The last digit of each division result corresponds to a digit of the original number n. Find the maximum value among these digits.

Algorithm implementation

Read the input value of n.

scanf("%lld", &n);

Find the maximum digit of the number n in the variable res.

res = 0;

Iterate through all the digits of n. To do this, repeatedly divide n by 10 and extract its last digit d = n % 10. Among all such digits d, determine the maximum value.

while (n > 0)

{

d = n % 10;

if (d > res) res = d;

n = n / 10;

}

Print the answer.

printf("%d\n", res);

Java implementation

import java.util.*;

public class Main

{

public static void main(String[] args)

{

Scanner con = new Scanner(System.in);

long n = con.nextLong();

long res = 0;

while (n > 0)

{

long d = n % 10;

if (d > res) res = d;

n = n / 10;

}

System.out.println(res);

con.close();

}

}

Python implementation

Read the input number as a string.

s = input()

The max() function returns the maximum character in the string.

· If the string consists only of digits, max() finds the largest digit (for example, for “534543”, the result will be “5”).

· If the string contains letters, the characters are compared in lexicographical order.

Print the answer.

print(max(s))