# Java Program to Find Maximum value possible by rotating digits of a given number

Given a positive integer N, the task is to find the maximum value among all the rotations of the digits of the integer N.

Examples:

Input: N = 657
Output: 765
Explanation: All rotations of 657 are {657, 576, 765}. The maximum value among all these rotations is 765.

Input: N = 7092
Output: 9270
Explanation:
All rotations of 7092 are {7092, 2709, 9270, 0927}. The maximum value among all these rotations is 9270.

Approach: The idea is to find all rotations of the number N and print the maximum among all the numbers generated. Follow the steps below to solve the problem:

• Count the number of digits present in the number N, i.e. upper bound of log10N.
• Initialize a variable, say ans with the value of N, to store the resultant maximum number generated.
• Iterate over the range [1, log10(N) – 1] and perform the following steps:
• Update the value of N with its next rotation.
• Now, if the next rotation generated exceeds ans, then update ans with the rotated value of N
• After completing the above steps, print the value of ans as the required answer.

Below is the implementation of the above approach:

## Java

 `// Java program for the above approach ` `import` `java.util.*; ` `class` `GFG ` `{ ` ` `  `// Function to find the maximum value ` `// possible by rotations of digits of N ` `static` `void` `findLargestRotation(``int` `num) ` `{ ` `   `  `    ``// Store the required result ` `    ``int` `ans = num; ` ` `  `    ``// Store the number of digits ` `    ``int` `len = (``int``)Math.floor(((``int``)Math.log10(num)) + ``1``); ` `    ``int` `x = (``int``)Math.pow(``10``, len - ``1``); ` ` `  `    ``// Iterate over the range[1, len-1] ` `    ``for` `(``int` `i = ``1``; i < len; i++) { ` ` `  `        ``// Store the unit's digit ` `        ``int` `lastDigit = num % ``10``; ` ` `  `        ``// Store the remaining number ` `        ``num = num / ``10``; ` ` `  `        ``// Find the next rotation ` `        ``num += (lastDigit * x); ` ` `  `        ``// If the current rotation is ` `        ``// greater than the overall ` `        ``// answer, then update answer ` `        ``if` `(num > ans) { ` `            ``ans = num; ` `        ``} ` `    ``} ` ` `  `    ``// Print the result ` `    ``System.out.print(ans); ` `} ` ` `  `// Driver Code ` `public` `static` `void` `main(String[] args) ` `{ ` `    ``int` `N = ``657``; ` `    ``findLargestRotation(N); ` `} ` `} ` ` `  `// This code is contributed by sanjoy_62.`

Output:

`765`

Time Complexity: O(log10N)
Auxiliary Space: O(1)

Please refer complete article on Maximum value possible by rotating digits of a given number for more details!

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