题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=1251
题意: 中文题诶~
思路: 字典树模板
代码1: 动态内存, 比较好理解一点, 不过速度略慢, 代码略长
1 #include <iostream> 2 #include <stdio.h> 3 #include <string.h> 4 using namespace std; 5 6 const int MAXN = 26; 7 const int MAX = 11; 8 char str[MAX]; 9 10 struct node{ 11 int count; 12 node *next[MAXN]; 13 node(){ 14 count = 0; 15 for(int i = 0; i < MAXN; i++){ 16 next[i] = NULL; 17 } 18 } 19 }; 20 21 void insert(node *p, char *str){ 22 for(int i = 0; str[i] != ' '; i++){ 23 int cnt = str[i] - 'a'; 24 if(p -> next[cnt] == NULL) p -> next[cnt] = new node(); 25 p = p -> next[cnt]; 26 p -> count++; 27 } 28 } 29 30 int query(node *p, char *str){ 31 for(int i = 0; str[i] != ' '; i++){ 32 int cnt = str[i] - 'a'; 33 p = p -> next[cnt]; 34 if(!p) return 0; 35 } 36 return p -> count; 37 } 38 39 void Free(node *p){ 40 if(!p) return; 41 for(int i = 0; i < MAXN; i++){ 42 if(p -> next[i]) Free(p -> next[i]); 43 } 44 free(p); 45 } 46 47 int main(void){ 48 node *root = new node(); 49 while(gets(str) && str[0] != ' '){ 50 insert(root, str); 51 } 52 while(gets(str)){ 53 printf("%d ", query(root, str)); 54 } 55 Free(root);//本题为单组输入,不释放空间也没影响 56 return 0; 57 }
代码2: 用数组模拟, 相对代码1略微难理解一点
1 #include <iostream> 2 #include <stdio.h> 3 #include <string.h> 4 using namespace std; 5 6 const int MAXN = 1e5 + 10; 7 int trie[MAXN << 2][26], sum[MAXN << 2], num = 1; 8 char str[11]; 9 //每个num对应一个节点,sum[i]为i出现的次数,trie[node][cnt]存储node这条链cnt节点后一个节点的位置,并标记当前节点是否存在 10 11 void insert(void){ 12 int node = 0, indx = 0; 13 while(str[indx]){ 14 int cnt = str[indx++] - 'a'; 15 if(!trie[node][cnt]) trie[node][cnt] = num++; 16 sum[trie[node][cnt]]++; 17 node = trie[node][cnt]; 18 } 19 } 20 21 int query(void){ 22 int node = 0, indx = 0; 23 while(str[indx]){ 24 int cnt = str[indx++] - 'a'; 25 if(!trie[node][cnt]) return 0; 26 node = trie[node][cnt]; 27 } 28 return sum[node]; 29 } 30 31 int main(void){ 32 while(gets(str) && str[0] != ' '){ 33 insert(); 34 } 35 while(gets(str)){ 36 printf("%d ", query()); 37 } 38 return 0; 39 }