计算给定字符串中每个单词的出现频率

给定一个字符串str ，任务是找到字符串中每个单词的频率。

例子：

Input: str = “Geeks For Geeks” 
Output: 
For 1 
Geeks 2 
Explanation: 
For occurs 1 time and Geeks occurs 2 times in the given string str.

Input: str = “learning to code is learning to create and innovate” 
Output: 
and 1 
code 1 
create 1 
innovate 1 
is 1 
learning 2 
to 2 
Explanation: 
The words and, code, create, innovate, is occurs 1 time; and learning, to occurs 2 times in the given string str. 

方法：要解决上述问题，我们必须按照以下步骤操作：

• 使用 Map 数据结构来存储字符串中每个单词的出现次数。
• 遍历整个字符串并检查当前单词是否存在于 map 中。如果存在，则更新当前单词的频率，否则插入频率为 1 的单词。
• 在地图中遍历并打印每个单词的频率。

下面是上述方法的实现：

C++

// C++ program to calculate the frequency
// of each word in the given string
 
#include 
using namespace std;
 
// Function to print frquency of each word
void printFrequency(string str)
{
    map M;
 
    // String for storing the words
    string word = "";
 
    for (int i = 0; i < str.size(); i++) {
 
        // Check if current character
        // is blank space then it
        // means we have got one word
        if (str[i] == ' ') {
 
            // If the current word
            // is not found then insert
            // current word with frequency 1
            if (M.find(word) == M.end()) {
                M.insert(make_pair(word, 1));
                word = "";
            }
 
            // update the frequency
            else {
                M[word]++;
                word = "";
            }
        }
 
        else
            word += str[i];
    }
 
    // Storing the last word of the string
    if (M.find(word) == M.end())
        M.insert(make_pair(word, 1));
 
    // Update the frequency
    else
        M[word]++;
 
    // Traverse the map
    // to print the  frequency
    for (auto& it : M) {
        cout << it.first << " - "
             << it.second
             << endl;
    }
}
 
// Driver Code
int main()
{
    string str = "Geeks For Geeks";
 
    printFrequency(str);
    return 0;
}

Java

// Java implementation of the above
// approach
 
import java.util.Map;
import java.util.TreeMap;
public class Frequency_Of_String_Words {
    
    // Function to count frequency of
    // words in the given string
    static void count_freq(String str)
    {
        Map mp=new TreeMap<>();
 
        // Splitting to find the word
        String arr[]=str.split(" ");
 
        // Loop to iterate over the words
        for(int i=0;i entry:
                    mp.entrySet())
        {
            System.out.println(entry.getKey()+
                    " - "+entry.getValue());
        }
    }
 
    // Driver Code
    public static void main(String[] args) {
        String str = "Geeks For Geeks";
 
        // Function Call
        count_freq(str);
    }
}

Python3

# Python3 program to calculate the frequency
# of each word in the given string
 
# Function to prfrquency of each word
def printFrequency(strr):
    M = {}
     
    # string for storing the words
    word = ""
     
    for i in range(len(strr)):
         
        # Check if current character
        # is blank space then it
        # means we have got one word
        if (strr[i] == ' '):
             
            # If the current word    
            # is not found then insert
            # current word with frequency 1
            if (word not in M):
                M[word] = 1
                word = ""
             
            # update the frequency
            else:
                M[word] += 1
                word = ""
         
        else:
            word += strr[i]
     
    # Storing the last word of the string
    if (word not in M):
        M[word] = 1
     
    # Update the frequency
    else:
        M[word] += 1
         
    # Traverse the map
    # to prthe frequency
    for it in M:
        print(it, "-", M[it])
     
# Driver Code
strr = "Geeks For Geeks"
printFrequency(strr)
 
# This code is contributed by shubhamsingh10

C#

// C# implementation of the above
// approach
using System;
using System.Collections.Generic;
 
class GFG{
 
// Function to count frequency of
// words in the given string
static void count_freq(String str)
{
    SortedDictionary mp = new SortedDictionary();
 
    // Splitting to find the word
    String []arr = str.Split(' ');
 
    // Loop to iterate over the words
    for(int i = 0; i < arr.Length; i++)
    {
         
        // Condition to check if the
        // array element is present
        // the hash-map
        if (mp.ContainsKey(arr[i]))
        {
            mp[arr[i]] = mp[arr[i]] + 1;
        }
        else
        {
            mp.Add(arr[i], 1);
        }
    }
     
    // Loop to iterate over the
    // elements of the map
    foreach(KeyValuePair entry in mp)
    {
        Console.WriteLine(entry.Key + " - " +
                          entry.Value);
    }
}
 
// Driver Code
public static void Main(String[] args)
{
    String str = "Geeks For Geeks";
 
    // Function call
    count_freq(str);
}
}
 
// This code is contributed by Rajput-Ji

输出：

For - 1
Geeks - 2

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