数据结构学习---链表的若干操作

在OJ上做了几道链表操作的题目，通过和别人代码的比较也尽量使代码简洁了一些。

 SDUT 2116 ~ 2122.

链表的结构体

struct node{
	int val;
	node *next;
	node(){
		val = 0; next = NULL;
	}
};

顺序与逆序读入链表

node* normalCreat(int n){ //正常的顺序读入 建立链表
	node *head,*p,*rear;
	head = new node;
	rear = head; //用rear来操纵
	for(int i=0;i<n;i++){
		p = new node;
		scanf("%d",&p->val);
		rear->next = p;
		rear = rear->next;
	}
	return head; //返回头节点
}
node* reverseCreat(int n){ //逆向建立链表
	node *head,*p;
	int i;
	head = new node;
	for(int i=0;i<n;i++){
		p = new node;
		scanf("%d",&p->val);
		p->next = head->next;  //这里的写法很巧妙 
		head->next = p;
	}
	return head;
}

合并两个有序的单链表

node* mergeList(node *a,node *b){ //返回合并后的两个链表， （并未删除原来的链表）
	a = a->next;  b = b->next;
	node *head = new node ;
	node *c = head;
	while(a && b){
		if(a->val > b->val){
			c->next = b;
			b = b->next;
			c = c->next;
		}
		else{
			c->next = a;
			a = a->next;
			c = c->next;
		}
	}
	while(a){
		c->next = a;
		a = a->next;
		c = c->next;
	}
	while(b){
		c->next = b;
		b = b->next;
		c = c->next;
	}
	return head;
}

将链表中的奇数，偶数各成一个链表

node *odd,*even; //奇数表， 偶数表
int oddNum,evenNum;
void divideList(node* head){ //将链表中分成两个链表 1.奇数链表 2.偶数链表
	even = new node;
	odd = new node;
	node* rear_even = even;
	node* rear_odd = odd;
	node* rear = head;
	rear = rear->next;
	while(rear){
		if(rear->val % 2){
			oddNum++;
			rear_odd->next = rear;
			rear = rear->next;
			rear_odd = rear_odd->next;
			rear_odd->next = NULL;
		}
		else{
			evenNum++;
			// cout<<rear->val<<"  bug"<<endl;
			rear_even->next = rear;
			rear = rear->next;
			rear_even = rear_even->next;
			rear_even->next = NULL;
		}
	}
}

删除链表中重复的元素

int del(node* head,int n){ //链表中 删除重复的元素
	node *p,*q,*t;
	p = head->next;
	while(p->next != NULL){
		q = p;
		t = q->next;
		while(t->next != NULL){
			if(t->val == p->val){
				q->next = t->next;
				delete t;
				t = q->next;
				n--;
			}
			else{
				q = t;
				t = t->next;
			}
		}
		if(t->next == NULL){
			if(t->val == p->val){
				q->next = NULL;
				delete t;
				n--;
			}
		}
		p = p->next;
	}
	return n;
}

有序读入链表

node* orCreat(int n){ //有序建立链表， 无序的读入数据，建立ascend（有序递增的表）
	node *head,*p,*rear;
	head = new node;
	rear = head;
	for(int i=0;i<n;i++){
		p = new node;
		rear = head;
		scanf("%d",&p->val);
		if(rear->next != NULL){
			while(1){
				if(rear->next->val>= p->val){
					p->next = rear->next;
					rear->next = p;
					break;
				}
				else 
					rear = rear->next; 
				if(rear->next == NULL){
					rear->next = p;
					break;
				}
			}
		}
		else
			head->next = p;
	}
	return head;
}

打印链表

void show(node *head){ //打印链表的元素
	node *p;
	p = head->next;
	while(p!=NULL){
		if(p->next != NULL)
			printf("%d ",p->val);
		else
			printf("%d\n",p->val);
		p = p->next;
	}
}