统计单词出现次数--hash表，二叉树，标准库

最新推荐文章于 2023-06-05 23:15:57 发布

iteye_14721

最新推荐文章于 2023-06-05 23:15:57 发布

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文章标签：数据结构与算法

本文探讨了如何使用C++的标准模板库进行高效数据操作，并通过实例展示了如何利用哈希表进行字符串计数及时间效率分析。

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我一直很喜欢用标准库，非常非常方便。但是有时候你根本不知道它为你做了什么，我喜欢知道自己写的程序每一步都干了什么！！！

////////////////////////////////// ///////////////////////////////// //标准模板库 ////////////////////////////////// /* #include <time.h> #include <map> #include <string> #include <fstream> #include <iostream> using namespace std; int main() { double beginTime = clock(); ifstream in("source.txt"); map<string, int> M; map<string, int>::iterator j; string t; while( in >> t ) { M[t]++; } for ( j = M.begin(); j != M.end(); j++) { cout << j->first << " " << j->second << endl; } double endTime = clock(); cout << "time: " << endTime - beginTime << "ms " << endl; return 0; } */ ////////////////////////////////// ///////////////////////////////// // 编程珠玑十五章，珍珠字符串 //用Hash表实现之 ////////////////////////////////// /* #include <time.h> #include <stdio.h> #include <string.h> #include <stdlib.h> #define NHASH 29989 #define MULT 31 typedef struct node *nodeptr; typedef struct node { char *word; int count; nodeptr next; }node; nodeptr bin[NHASH]; unsigned int hash( char *p) { unsigned int h = 0; for( ; *p; p++) { h = MULT * h + *p; } return h % NHASH; } void incword( char *s) { int h = hash( s ); nodeptr p = NULL; for ( p = bin[h]; p != NULL; p = p->next) { if ( strcmp( s, p->word) == 0) { p->count ++; return; } } p = NULL; p = new node; if ( p == NULL) { return; } p->count = 1; p->word = new char[ strlen(s) + 1]; strcpy( p->word, s); p->next = bin[h]; bin[h] = p; } int main() { double beginTime = clock(); int i = 0; FILE *fp = NULL; fp = fopen("source.txt","r"); if ( fp == NULL ) { printf("文件打开错误"); return 1; } //ifstream in("source.txt"); for ( i = 0; i < NHASH; i++) { bin[i] = NULL; } char tempWord[100]; while( fscanf(fp, "%s", tempWord) != EOF ) { incword( tempWord ); } nodeptr p = NULL; for ( i = 0; i < NHASH; i++) { p = NULL; for ( p = bin[i]; p != NULL; p = p->next) { //cout << p->word<< " " << p->count << endl; printf("%s %d\n", p->word, p->count); } } double endTime = clock(); printf("time:%g ms", endTime - beginTime ); return 0; } */ #include <stdio.h> #include <string.h> #include <stdlib.h> #include <time.h> typedef struct node *nodeptr; typedef struct node { char *word; int count; nodeptr lchild; nodeptr rchild; }node; nodeptr setUp( nodeptr root, char *s) { if ( root == NULL ) { root = (nodeptr)malloc( sizeof(node)); root->word = (char *)malloc(strlen(s) + 1); strcpy( root->word, s); root ->lchild = NULL; root ->rchild = NULL; root->count = 1; return root; } int flag = strcmp( root->word, s); if( !flag) { root ->count ++; return root; } else if ( flag < 0 ) { root ->rchild = setUp( root->rchild, s); } else { root->lchild = setUp(root->lchild, s); } return root; } void Traverse( nodeptr root) { if ( root != NULL) { if ( root->rchild != NULL) { Traverse(root->rchild); } printf("%s %d\n", root->word, root->count); if ( root->lchild != NULL) { Traverse(root->lchild); } } return ; } int main() { nodeptr root = NULL; double beginTime = clock(); int i = 0; FILE *fp = NULL; fp = fopen("source.txt","r"); if ( fp == NULL ) { printf("文件打开错误"); return 1; } char tempWord[100]; while( fscanf(fp, "%s", tempWord) != EOF ) { root = setUp(root, tempWord ); } Traverse(root); double endTime = clock(); printf("time:%g ms", endTime - beginTime ); return 0; }