題目: 判斷兩個無環鏈表是否相交
public class LinkedList {
public void print(LinkedNode<Integer> root){
LinkedNode<Integer> tmp = root;
while (tmp!=null){
System.out.print(tmp.value+" ");
tmp = tmp.next;
}
System.out.println();
}
//創建鏈表
public LinkedNode<Integer> constructLinkedList(LinkedNode<Integer>... nodes){
LinkedNode<Integer> root = new LinkedNode<>(0);
LinkedNode<Integer> tmp = root;
for(LinkedNode<Integer> node:nodes){
tmp.next = node;
tmp = tmp.next;
}
return root.next;
}
/**
* 3、如何判斷兩個無環鏈表是否相交
* 思路:1、看一下兩個鏈表的尾結點是否相同
* 擴展:找到相交的節點,第一遍遍歷兩者的長度分別爲 len1 與 len2 ,算出兩者的diff,
* 比較長的鏈表先將其頭指針移動 diff個距離,然後兩個鏈表的頭指針開始同時往下遍歷,指導兩者頭指針指向同一個對象,
* 則該對象就位所找的相交節點
*/
@Test
public void test3(){
LinkedNode<Integer> node11 = new LinkedNode<>(1);
LinkedNode<Integer> node12 = new LinkedNode<>(3);
LinkedNode<Integer> node13 = new LinkedNode<>(5);
LinkedNode<Integer> node14 = new LinkedNode<>(8);
LinkedNode<Integer> node15 = new LinkedNode<>(9);
LinkedNode<Integer> node16 = new LinkedNode<>(10);
LinkedNode<Integer> node17 = new LinkedNode<>(12);
LinkedNode<Integer> node18 = new LinkedNode<>(11);
LinkedNode<Integer> node19 = new LinkedNode<>(17);
LinkedNode<Integer> node22 = new LinkedNode<>(4);
LinkedNode<Integer> node23 = new LinkedNode<>(6);
LinkedNode<Integer> node24 = new LinkedNode<>(7);
LinkedNode<Integer> node25 = new LinkedNode<>(13);
//構建兩個鏈表:
// root1: 1 -> 3 -> 5 -> 8-> 9 ,記爲鏈表 1
// root2: 2 -> 4 -> 6 -> 7-> 10,記爲鏈表 2
LinkedNode<Integer> root1 = constructLinkedList(node11,node12,node13,node14,node15,node16,node17,node18,node19);
LinkedNode<Integer> root2 = constructLinkedList(node22,node23,node24,node25,node16,node17,node18,node19);
LinkedNode<Integer> tmp1 = root1;
LinkedNode<Integer> tmp2 = root2;
int len1 = 1;
int len2 = 1;
while (tmp1.next !=null){
tmp1 = tmp1.next;
len1 ++;
}
while (tmp2.next !=null){
tmp2 = tmp2.next;
len2 ++;
}
if(tmp1.value == tmp2.value){
System.out.println("two list have cross point: ");
}else {
System.out.println("two list do not have cross point: ");
}
System.out.println("len1: "+len1+", len2: "+len2);
//如果相交,求出第一個相交的節點;
if(len1>len2){
int diff = len1 - len2;
LinkedNode<Integer> tmp11 = root1;
LinkedNode<Integer> tmp22 = root2;
while (diff>0){
tmp11 = tmp11.next;
diff --;
}
while (tmp11.value !=tmp22.value){
if(tmp11.next == null||tmp22.next == null){
break;
}
tmp11 = tmp11.next;
tmp22 = tmp22.next;
}
System.out.println("cross point:"+tmp11.value);
}else{
int diff = len1 - len2;
LinkedNode<Integer> tmp11 = root2;
LinkedNode<Integer> tmp22 = root1;
while (diff>0){
tmp11 = tmp11.next;
diff --;
}
while (tmp11.value !=tmp22.value){
if(tmp11.next == null||tmp22.next == null){
break;
}
tmp11 = tmp11.next;
tmp22 = tmp22.next;
}
System.out.println("cross point:"+tmp11.value);
}
}
}
輸出:
two list have cross point:
len1: 9, len2: 8
cross point:10