POJ 2887

题意：在字符串中插入字符，问第i个字符是谁

题解：块状链表，不知为什么splay超时= =！

View Code

 1 #include<cstdio>

 2 #include<cstring>

 3 #include<cmath>

 4 #include<algorithm>

 5 using namespace std;

 6 const int maxn=1005000;

 7 int bs,top;

 8 struct Block

 9 {

10     int size,next;

11     char s[3000];

12     void push_back(char ch)

13     {

14         s[size++]=ch;

15     }

16     void insert(int pos,char ch)

17     {

18         for(int i=size++;i>pos;i--)

19             s[i]=s[i-1];

20         s[pos]=ch;

21     }

22 }block[3000];

23 void update(int x)

24 {

25     if(block[x].size<bs*2)

26         return;

27     ++top;

28     int i,j,k=block[x].size;

29     for(i=bs,j=0;i<k;i++,j++)

30         block[top].s[j]=block[x].s[i];

31     block[top].size=j;

32     block[x].size=bs;

33     block[top].next=block[x].next;

34     block[x].next=top;

35 }

36 int main()

37 {

38     char s[maxn];

39     gets(s);

40     int len=strlen(s),m;

41     scanf("%d",&m);

42     bs=sqrt((double)(len+m))+1;

43     top=0;

44     block[0].size=0;

45     for(int i=0;i<len;i++)

46     {

47         if(block[top].size==bs)

48         {

49             block[top].next=top+1;

50             block[++top].size=0;

51         }

52         block[top].push_back(s[i]);

53     }

54     block[top].next=-1;

55     while(m--)

56     {

57         char op,ch;

58         int pos,k;

59         scanf(" %c",&op);

60         if(op=='Q')

61         {

62             scanf("%d",&pos);

63             k=0;

64             while(pos>block[k].size)

65                 pos-=block[k].size,k=block[k].next;

66             printf("%c\n",block[k].s[pos-1]);

67         }

68         else

69         {

70             scanf(" %c %d",&ch,&pos);

71             k=0;

72             while(block[k].next!=-1&&pos>block[k].size)

73                 pos-=block[k].size,k=block[k].next;

74             block[k].insert(min(pos-1,block[k].size+1),ch);

75             update(k);

76         }

77     }

78     return 0;

79 }