Given a non-negative integer, you could swap two digits at most once to get the maximum valued number. Return the maximum valued number you could get.
Example 1:
Input: 2736 Output: 7236 Explanation: Swap the number 2 and the number 7.
Example 2:
Input: 9973 Output: 9973 Explanation: No swap.
Note:
- The given number is in the range [0, 108]
Approach #1: Math. [Java]
class Solution {
public int maximumSwap(int num) {
char[] digits = Integer.toString(num).toCharArray();
int[] buckets = new int[10];
for (int i = 0; i < digits.length; ++i)
buckets[digits[i]-‘0‘] = i;
for (int i = 0; i < digits.length; ++i) {
for (int j = 9; j > digits[i]-‘0‘; --j) {
if (buckets[j] > i) {
char temp = digits[i];
digits[i] = digits[buckets[j]];
digits[buckets[j]] = temp;
return Integer.valueOf(new String(digits));
}
}
}
return num;
}
}
Analysis:
https://leetcode.com/problems/maximum-swap/discuss/107068/Java-simple-solution-O(n)-time
原文：https://www.cnblogs.com/ruruozhenhao/p/10655283.html