Question Definition
Given a non-negative integer N, find the largest number that is less than or equal to N with monotone increasing digits.
(Recall that an integer has monotone increasing digits if and only if each pair of adjacent digits x and y satisfy x <= y.) Example 1:
Input: N = 10
Output: 9
Example 2:
Input: N = 1234
Output: 1234
Example 3:
Input: N = 332
Output: 299
Note: N is an integer in the range [0, 10^9].
Java Solution
public int monotoneIncreasingDigits(int N) {
char[] nums = Integer.toString(N).toCharArray();
int index = 0;
while(index < nums.length - 1 && nums[index] <= nums[index + 1])
index++;
while(index > 0 && nums[index] == nums[index - 1]) index--;
if(index == nums.length - 1) return N;
nums[index] = (char)(((int)(nums[index] - '0') - 1) + '0');
while(++index < nums.length) nums[index] = '9';
return Integer.parseInt(new String(nums));
}
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