题目
You have to create a function that takes a positive integer number and returns the next bigger number formed by the same digits:
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Kata.nextBiggerNumber(<span class="hljs-number">12</span>)==<span class="hljs-number">21</span> Kata.nextBiggerNumber(<span class="hljs-number">513</span>)==<span class="hljs-number">531</span> Kata.nextBiggerNumber(<span class="hljs-number">2017</span>)==<span class="hljs-number">2071</span> |
If no bigger number can be composed using those digits, return -1:
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Kata.nextBiggerNumber(<span class="hljs-number">9</span>)==-<span class="hljs-number">1</span> Kata.nextBiggerNumber(<span class="hljs-number">111</span>)==-<span class="hljs-number">1</span> Kata.nextBiggerNumber(<span class="hljs-number">531</span>)==-<span class="hljs-number">1</span> |
题解
题意大概是找到一个数组成数字相同的，大一点的那个数。
实际上只要使用程序将我们解决这道题的思路翻译一遍就行了，先找出最低的可以变大的位（这个位的更低位有一个尽量小，但是比他大的数），交换后，将比他低的位从小到大排序。
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import java.util.*; public class Kata { public static long nextBiggerNumber(long n) { char[] s = Long.valueOf(n).toString().toCharArray(); boolean flag = false; for (int i=s.length-1;i>=0;i--) { int pos = -1; for (int j=s.length-1;j>i;j--) { if (s[j] > s[i] && (pos == -1 || s[j] < s[pos])) { pos = j; } } if (pos != -1) { char t = s[pos]; s[pos] = s[i]; s[i] = t; Arrays.sort(s,i+1,s.length); flag = true; break; } } if (flag == false) return -1; else return Long.valueOf(new String(s)).longValue(); } } |