冒泡排序

        for(int i =0;i<arr.length-1;i++) {            for(int j=0;j<arr.length-i-1;j++) {//-1为了防止溢出                if(arr[j]>arr[j+1]) {                    int temp = arr[j];                    arr[j]=arr[j+1];                    arr[j+1]=temp;                }            }        }    }

二分查找法

给定数组是按从小到大排序好的

        //先排序        bubbleSort(arr);        int left = 0;        int right = arr.length - 1;        int mid;        while(left <= right){            mid = (left + right) % 2 == 0 ? (left + right) / 2 : (left + right) / 2 + 1;            if(arr[mid] > val){                right = mid  ;            }else if (arr[mid] < val){                left = mid ;            }else{                //找到该值             **   System.out.println(mid);**                return;            }        }    }

单链表反转

public class Single edList{      private static class Node{          private int val;          private Node next;        }      //递归反转1-2-3-4      public Node reverse1(Node node){          if(node.next ==null || node== null){            return node;          }          Node temp= node.next;          Node newNode = reverse1(node.next);          node.next = null;          temp.next = node;          return newNode;       }      //遍历1-2-3-4    public Node reverse2(Node head){       Node prev = null;       Node next = null;       while (head != null){           next =  head.next;           head.next = prev;  //在这里完成4->3->2->1           prev = head;           head = next;       }       return prev;    }}