738 Monotone Increasing Digits

Given a non-negative integerN, find the largest number that is less than or equal toNwith monotone increasing digits.

(Recall that an integer hasmonotone increasing digitsif and only if each pair of adjacent digitsxandysatisfyx <= y.)

Example 1:

Input:
 N = 10

Output:
 9

Example 2:

Input:
 N = 1234

Output:
 1234

Example 3:

Input:
 N = 332

Output:
 299

Note:Nis an integer in the range[0, 10^9].

Solution)

class Solution {
    public int monotoneIncreasingDigits(int N) {
        char[] x = String.valueOf(N).toCharArray();

        int mark = x.length;
        for(int i = x.length-1;i>0;i--){
            if(x[i]<x[i-1]){
                mark = i-1;
                x[i-1]--;
            }
        }
        for(int i = mark+1;i<x.length;i++){
            x[i] = '9';
        }
        return Integer.parseInt(new String(x));
    }
}