POJ 2887 Big String

来源：互联网发布：tomcat源码有必要编辑：程序博客网时间：2024/06/07 01:35

分析：给你一串字符，让你进行一系列插入和查询操作，查询时输出第p个字符，数组插入慢，链表查找快，于是我们用块状链表。

# include <stdio.h># include <malloc.h># include <string.h>  typedef struct node  {      int len;      char a[1005];      struct node *next;  }Node;  int max;  Node *Create()  {      int i,n,start=0;      char s[1000005];      Node *head=NULL,*p,*q;      scanf("%s",s);      n=strlen(s);      max=n;      while(start<n)      {          p=(Node *)malloc(sizeof(Node));          if(n-start>1000)            p->len=1000;           else            p->len=n-start;            for(i=1;i<=p->len;i++)                p->a[i]=s[start+i-1];            p->next=NULL;            if(head==NULL)                head=p;            else                q->next=p;            q=p;            start+=p->len;      }      return head;  }  void Insert(Node *head)  {      int i,k;      char c;      Node *p;      getchar();      scanf("%c %d",&c,&k);      if(k>max)      {          k=max+1;          while(head->next)          {              k-=head->len;              head=head->next;          }      }      else      {          while(k>head->len)          {          k=k-head->len;          head=head->next;          }          for(i=head->len;i>=k;i--)          head->a[i+1]=head->a[i];      }      head->a[k]=c;      (head->len)++;      max++;      if(head->len>1000)      {          p=(Node *)malloc(sizeof(Node));          p->len=1;          p->a[1]=head->a[head->len];          (head->len)--;          p->next=head->next;          head->next=p;      }  }  void query(Node *head)  {      int k;      scanf("%d",&k);      while(k>head->len)      {          k=k-head->len;          head=head->next;      }      printf("%c\n",head->a[k]);  }  int main()  {      int t;      char ch;      Node *head=Create();      scanf("%d",&t);      while(t--)      {          getchar();          scanf("%c",&ch);          if(ch=='I')            Insert(head);          else            query(head);      }      return 0;  }

0 0