针对Comparator接口实现类进行总结

淡淡的烟草味﹌ 2023-01-09 15:32 147阅读 0赞

在做数组排成最小的数算法题时，对重写比较器进行了研究，现在进行总结。  
题目[https://www.nowcoder.com/practice/8fecd3f8ba334add803bf2a06af1b993?tpId=13&&tqId=11185&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking][https_www.nowcoder.com_practice_8fecd3f8ba334add803bf2a06af1b993_tpId_13_tqId_11185_rp_1_ru_ta_coding-interviews_qru_ta_coding-interviews_question-ranking]

*  小根堆排序

[https://leetcode-cn.com/problems/ba-shu-zu-pai-cheng-zui-xiao-de-shu-lcof/solution/mian-shi-ti-45-ba-shu-zu-pai-cheng-zui-xiao-de-s-4/492343][https_leetcode-cn.com_problems_ba-shu-zu-pai-cheng-zui-xiao-de-shu-lcof_solution_mian-shi-ti-45-ba-shu-zu-pai-cheng-zui-xiao-de-s-4_492343]  
***JAVA默认是从小到大排序！！！***

Queue<String> queue = new PriorityQueue<>(new Comparator<String>() { 
                @Override
                public int compare(String o1, String o2) { 
                    //字典序列小的放在堆顶
                    return (o1 + o2).compareTo(o2 + o1);
                }
            });

需要注意的是，尽管是Comparator重写compare方法返回的是int，规则可以自定义，但是返回1说明不交换o1和o2，返回-1则交换。

*  重写Arrays.sort也可以

Arrays.sort(arr,new Comparator<String>(){ 
                 public int compare(String s1,String s2){ 
                     if((s1+s2).compareTo(s2+s1)>=0) return 1;
                     else return -1;
                 }
             } );

*  使用lambda表达式重写 （由测试得知这一表达式会导致算法效率变慢！）

Arrays.sort(arr,(String s1,String s2)->{                        
     //当接口只有一个抽象函数时，用->{}程序块代替定义 
                     if((s1+s2).compareTo(s2+s1)>=0) return 1;
                     else return -1;
                 }  );

[https_www.nowcoder.com_practice_8fecd3f8ba334add803bf2a06af1b993_tpId_13_tqId_11185_rp_1_ru_ta_coding-interviews_qru_ta_coding-interviews_question-ranking]: https://www.nowcoder.com/practice/8fecd3f8ba334add803bf2a06af1b993?tpId=13&&tqId=11185&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking
[https_leetcode-cn.com_problems_ba-shu-zu-pai-cheng-zui-xiao-de-shu-lcof_solution_mian-shi-ti-45-ba-shu-zu-pai-cheng-zui-xiao-de-s-4_492343]: https://leetcode-cn.com/problems/ba-shu-zu-pai-cheng-zui-xiao-de-shu-lcof/solution/mian-shi-ti-45-ba-shu-zu-pai-cheng-zui-xiao-de-s-4/492343