劍指offer——（6）從尾到頭列印連結串列&&反轉連結串列&&連結串列倒數第K個結點
阿新 • • 發佈：2018-11-12
/** * public class ListNode { * int val; * ListNode next = null; * * ListNode(int val) { * this.val = val; * } * } * */ import java.util.ArrayList; public class Solution { //ListNode head = null; ArrayList<Integer> AL = new ArrayList<Integer>(); public ArrayList<Integer> printListFromTailToHead(ListNode listNode) { if(listNode==null) return AL; //System.out.println("listNode："+listNode.val); int count=1; ListNode ln = listNode; while(ln.next!=null){ count++; ln = ln.next; } int arr[] = new int[count]; /*arr[count-1] = in2.val; in2 = in2.next;*/ while(listNode!=null){ arr[count-1] = listNode.val; if(listNode.next==null) break; listNode = listNode.next; count--; } for(Integer i=0;i<arr.length;i++){ AL.add(arr[i]); } return AL; } }
/* public class ListNode { int val; ListNode next = null; ListNode(int val) { this.val = val; } }*/ import java.util.ArrayList; public class Solution { ListNode head = null; ArrayList<Integer> AL = new ArrayList<Integer>(); public ListNode ReverseList(ListNode listNode) { head = listNode; while(head!=null){ AL.add(head.val); head = head.next; } int count = AL.size()-1; ListNode temp = null; for(int i = count;i>=0;i--) { listNode.val = AL.get(i); if(i==count) temp = listNode; listNode = listNode.next; } return temp; } }
/* public class ListNode { int val; ListNode next = null; ListNode(int val) { this.val = val; } }*/ public class Solution { public ListNode FindKthToTail(ListNode listNode,int k) { if(listNode==null) return listNode; int count = 0; ListNode head = listNode; while(head!=null){ count++; head = head.next; } if(k>count) return null; for(int i = 0;i<count-k;i++) { listNode = listNode.next; } return listNode; } }