最大长度的子串与字符串最高频率

给定一个字符串。任务是找到最大长度的最大出现子字符串。这些情况可能会重叠。
例子：

Input: str = "abab"
Output: ab
"a", "b", "ab" are occur 2 times. But, "ab" has maximum length

Input: str = "abcd"
Output: a

方法：想法是使用地图存储每个子字符串的频率，并以最大频率和最大长度打印该子字符串。
下面是上述方法的实现：

C++

// C++ program to find maximum
// occurred substring of a string
#include 
using namespace std;
 
// function to return maximum
// occurred substring of a string
string MaxFreq(string str)
{
    // size of the string
    int n = str.size();
 
    unordered_map m;
 
    for (int i = 0; i < n; i++) {
        string s = "";
        for (int j = i; j < n; j++) {
            s += str[j];
            m[s]++;
        }
    }
 
    // to store maximum frequency
    int maxi = 0;
 
    // to store string which has maximum frequency
    string s;
    for (auto i = m.begin(); i != m.end(); i++) {
        if (i->second > maxi) {
            maxi = i->second;
            s = i->first;
        }
        else if (i->second == maxi) {
            string ss = i->first;
            if (ss.size() > s.size())
                s = ss;
        }
    }
 
    // return substring which has maximum frequency
    return s;
}
 
// Driver program
int main()
{
    string str = "ababecdecd";
 
    // function call
    cout << MaxFreq(str);
 
    return 0;
}

Java

// Java program to find maximum
// occurred subString of a String
import java.util.*;
class GFG{
 
// Function to return maximum
// occurred subString of a String
static String MaxFreq(String str)
{
  // Size of the String
  int n = str.length();
 
  Map mp = new HashMap();
 
  for (int i = 0; i < n; i++)
  {
    String s = "";
    for (int j = i; j < n; j++)
    {
      s += str.charAt(j);
      if(mp.containsKey(s))
      {
        mp.put(s, mp.get(s) + 1);
      }
      else
      {
        mp.put(s, 1);
      }
    }
  }
 
  // To store maximum frequency
  int maxi = 0;
 
  // To store String which
  // has maximum frequency
  String s = "";
  for (Map.Entry i : mp.entrySet())
  {
    if (i.getValue() > maxi)
    {
      maxi = i.getValue();
      s = i.getKey();
    }
    else if (i.getValue() == maxi)
    {
      String ss = i.getKey();
      if (ss.length() > s.length())
        s = ss;
    }
  }
 
  // Return subString which
  // has maximum frequency
  return s;
}
 
// Driver code
public static void main(String[] args)
{
  String str = "ababecdecd";
 
  // Function call
  System.out.print(MaxFreq(str));
}
}
 
// This code is contributed by shikhasingrajput

Python3

# Python3 program to find maximum
# occured of a string
 
# function to return maximum occurred
# substring of a string
def MaxFreq(s):
     
    # size of string
    n = len(s)
     
    m = dict()
     
    for i in range(n):
        strng = ''
        for j in range(i, n):
            strng += s[j]
            if strng in m.keys():
                m[strng] += 1
            else:
                m[strng] = 1
                 
    # to store maximum freqency
    maxi = 0
     
    # To store string which has
    # maximum frequency
    maxi_str = ''
     
    for i in m:
        if m[i] > maxi:
            maxi = m[i]
            maxi_str = i
        elif m[i] == maxi:
            ss = i
            if len(ss) > len(maxi_str):
                maxi_str = ss
                 
    # return substring which has maximum freq
    return maxi_str
     
# Driver code
strng = "ababecdecd"
 
print(MaxFreq(strng))
         
# This code is contributed by Mohit kumar 29

C#

// C# program to find maximum
// occurred substring of a string
using System;
using System.Collections.Generic;
 
class GFG{
 
// Function to return maximum
// occurred substring of a string
static string MaxFreq(string str)
{
     
    // Size of the string
    int n = str.Length;
     
    Dictionary m = new Dictionary();
                         
    for(int i = 0; i < n; i++)
    {
        string sp = "";
        for(int j = i; j < n; j++)
        {
            sp += str[j];
            if(m.ContainsKey(sp))
            {
                m[sp]++;
            }
            else
            {
                m[sp] = 1;
            }
        }
    }
 
    // To store maximum frequency
    int maxi = 0;
 
    // To store string which has maximum frequency
    string s = "";
     
    foreach(KeyValuePair i in m)
    {
        if (i.Value > maxi)
        {
            maxi = i.Value;
            s = i.Key;
        }
        else if (i.Value == maxi)
        {
            string ss = i.Key;
            if (ss.Length > s.Length)
                s = ss;
        }
    }
 
    // Return substring which has
    // maximum frequency
    return s;
}
 
// Driver Code
public static void Main(string[] args)
{
    string str = "ababecdecd";
 
    // Function call
    Console.Write(MaxFreq(str));
}
}
 
// This code is contributed by rutvik_56

输出：

ecd

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