0x13 链表与邻接表

Posted 2022-03-07 kkkstra

链表的两种写法

指针实现

 1 // 双向链表
 2 struct Node 
 3     int value; // data
 4     Node *prev, *next; // pointers
 5 ;
 6 Node *head, *tail;
 7 
 8 void initialize()  // create an empty list
 9     head = new Node();
10     tail = new Node();
11     head->next = tail;
12     tail->prev = head;
13 
14 
15 void insert(Node *p, int value)  // insert data after p
16     q = new Node();
17     q->value = value;
18     p->next->prev = q; q->next = p->next;
19     p->next = q; q->prev = p;
20 
21 
22 void remove(Node *p)  // remove p
23     p->prev->next = p->next;
24     p->next->prev = p->prev;
25     delete p;
26 
27 
28 void recycle()  // release memory
29     while (head != tail) 
30         head = head->next;
31         delete head->prev;
32     
33     delete tail;
34 

数组实现

 1 // 数组模拟链表
 2 struct Node 
 3     int value;
 4     int prev, next;
 5  node[SIZE];
 6 int head, tail, tot;
 7 
 8 int initialize() 
 9     tot = 2;
10     head = 1, tail = 2;
11     node[head].next = tail;
12     node[tail].prev = head;
13 
14 
15 int insert(int p, int value) 
16     q = ++tot;
17     node[q].value = value;
18     node[node[p].next].prev = q;
19     node[q].next = node[p].next;
20     node[p].next = q; node[q].prev = p;
21 
22 
23 void remove(int p) 
24     node[node[p].prev].next = node[p].next;
25     node[node[p].next].prev = node[p].prev;
26 

邻接表的插入和查找

 1 // 邻接表：加入有向边(x, y)，权值为z
 2 void add(int x, int y, int z) 
 3     ver[++tot] = y, edge[tot] = z; // 真实数据
 4     next[tot] = head[x], head[x] = tot; // 在表头x处插入
 5 
 6 
 7 // 邻接表：访问从x出发的所有边
 8 for (int i = head[x]; i; i = next[i]) 
 9     int y = ver[i], z = edge[i];
10     // 一条有向边(x, y)，权值为z
11 

【例题】CH1301 邻值查找

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cmath>
 4 #include <cstring>
 5 #include <algorithm>
 6 #include <set>
 7 using namespace std;
 8 const int INF=0x3f3f3f3f;
 9 const int maxn=300000+10;
10 int n;
11 
12 struct node 
13     int v, index;
14     bool operator < (const node &a) const 
15         return v<a.v;
16     
17 ;
18 set<node> s;
19 
20 int main() 
21     int n;
22     scanf("%d", &n);
23     int x;
24     scanf("%d", &x);
25     s.insert((node)x,1);
26     for (int i=2; i<=n; ++i) 
27         scanf("%d", &x);
28         set<node>::iterator r=s.lower_bound((node)x,0), l=r;
29         --l;
30         if (r==s.end()) 
31             printf("%d %d\n", x-(l->v), l->index);
32         
33         else if(r==s.begin()) 
34             printf("%d %d\n", (r->v)-x, r->index);
35         
36         else if (x-(l->v)<=(r->v)-x) 
37             printf("%d %d\n", x-(l->v), l->index);
38         
39         else 
40             printf("%d %d\n", (r->v)-x, r->index);
41         
42         s.insert((node)x,i);
43     
44     return 0;
45   

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