块状链表第一题，懒得写成链表形式的，所以写成了静态链表。
思想还是很简单的，就是进行分块查找和插入，和建立索引有点像，复杂度是根号的，实现起来比较容易，由于这个题插入操作不多，所以没有写split函数，
因为没有删除操作，所以也没有写union函数，随后有空再补上吧。
1 #include <iostream> 2 #include <cstring> 3 #include <cstdio> 4 #include <cmath> 5 using namespace std; 6 7 const int N = 1002001; 8 const int M = 2000; 9 char str[N]; 10 11 struct Block 12 { 13 char ch[M]; 14 int size; 15 int next; 16 17 void init() 18 { 19 size = 0; 20 next = -1; 21 } 22 23 }; 24 25 struct BlockList 26 { 27 int head, len; 28 Block b[M]; 29 30 void init( char * s ) 31 { 32 len = strlen(s); 33 int as = sqrt( ( double ) len ); 34 head = 0; 35 int j = head; 36 b[j].init(); 37 for ( int i = 0; i < len; i++ ) 38 { 39 if ( b[j].size == as ) 40 { 41 b[j].next = j + 1; 42 j++; 43 b[j].init(); 44 } 45 b[j].ch[b[j].size++] = s[i]; 46 } 47 } 48 49 //插在第pos个元素前面 50 void insert( int pos, char v ) 51 { 52 if ( pos > len ) 53 { 54 int i = head, j = b[head].next; 55 while ( j != -1 ) 56 { 57 i = b[i].next; 58 j = b[j].next; 59 } 60 b[i].ch[b[i].size++] = v; 61 len++; 62 return ; 63 } 64 int i = head; 65 while ( pos > b[i].size ) 66 { 67 pos -= b[i].size; 68 i = b[i].next; 69 } 70 for ( int j = b[i].size; j >= pos; j-- ) 71 { 72 b[i].ch[j] = b[i].ch[j - 1]; 73 } 74 b[i].ch[pos - 1] = v; 75 b[i].size++; 76 len++; 77 return ; 78 } 79 80 char at( int pos ) 81 { 82 int i = head; 83 while ( pos > b[i].size ) 84 { 85 pos -= b[i].size; 86 i = b[i].next; 87 } 88 return b[i].ch[pos - 1]; 89 } 90 91 } bl; 92 93 int main() 94 { 95 while ( scanf("%s", str) != EOF ) 96 { 97 bl.init(str); 98 int n; 99 char op[2]; 100 scanf("%d", &n); 101 while ( n-- ) 102 { 103 scanf("%s", op); 104 if ( op[0] == 'I' ) 105 { 106 char ch[2]; 107 int p; 108 scanf("%s%d", ch, &p); 109 bl.insert( p, ch[0] ); 110 } 111 else 112 { 113 int p; 114 scanf("%d", &p); 115 char ans = bl.at(p); 116 printf("%c ", ans); 117 } 118 } 119 } 120 return 0; 121 }