给定字符串S。任务是按字典顺序打印第K个s的不同子字符串中最小的一个。
s的子字符串是通过去除s中的非空连续部分而获得的字符串。
例如,如果s = ababc,则a,bab和ababc是s的子字符串,而ac,z和空字符串则不是。另外,我们说子字符串与字符串不同时也不同。
例子:
Input: str = “aba”, k = 4
Output: b
All unique substrings are a, ab, aba, b, ba.
Thus the 4th lexicographically smallest substring is b.
Input: str = “geeksforgeeks”, k = 5
Output: eeksf
方法:对于任意字符串t,其每个适当的后缀在字典上小于t,并且t的字典等级至少为| t |。因此,答案的长度最多为K。
生成s的所有子串,它们的长度最大为K。对它们进行排序,唯一化并打印第K个子串,其中N = | S |。
下面是上述方法的实现:
C++
// C++ implementation of the above approach
#include
using namespace std;
void kThLexString(string st, int k, int n)
{
// Set to store the unique substring
set z;
for(int i = 0; i < n; i++)
{
// String to create each substring
string pp;
for(int j = i; j < i + k; j++)
{
if (j >= n)
break;
pp += st[j];
// Adding to set
z.insert(pp);
}
}
// Converting set into a list
vector fin(z.begin(), z.end());
// Sorting the strings int the list
// into lexicographical order
sort(fin.begin(), fin.end());
// Printing kth substring
cout << fin[k - 1];
}
// Driver code
int main()
{
string s = "geeksforgeeks";
int k = 5;
int n = s.length();
kThLexString(s, k, n);
}
// This code is contributed by yatinagg
Java
// Java implementation of
// the above approach
import java.util.*;
class GFG{
public static void kThLexString(String st,
int k, int n)
{
// Set to store the unique substring
Set z = new HashSet();
for(int i = 0; i < n; i++)
{
// String to create each substring
String pp = "";
for(int j = i; j < i + k; j++)
{
if (j >= n)
break;
pp += st.charAt(j);
// Adding to set
z.add(pp);
}
}
// Converting set into a list
Vector fin = new Vector();
fin.addAll(z);
// Sorting the strings int the list
// into lexicographical order
Collections.sort(fin);
// Printing kth substring
System.out.print(fin.get(k - 1));
}
// Driver Code
public static void main(String[] args)
{
String s = "geeksforgeeks";
int k = 5;
int n = s.length();
kThLexString(s, k, n);
}
}
// This code is contributed by divyeshrabadiya07
Python3
# Python3 implementation of the above approach
def kThLexString(st, k, n):
# Set to store the unique substring
z = set()
for i in range(n):
# String to create each substring
pp = ""
for j in range(i, i + k):
if (j >= n):
break
pp += s[j]
# adding to set
z.add(pp)
# converting set into a list
fin = list(z)
# sorting the strings int the list
# into lexicographical order
fin.sort()
# printing kth substring
print(fin[k - 1])
s = "geeksforgeeks"
k = 5
n = len(s)
kThLexString(s, k, n)
C#
// C# implementation of
// the above approach
using System;
using System.Collections.Generic;
using System.Collections;
class GFG{
public static void kThLexString(string st,
int k, int n)
{
// Set to store the unique substring
HashSet z = new HashSet();
for(int i = 0; i < n; i++)
{
// String to create each substring
string pp = "";
for(int j = i; j < i + k; j++)
{
if (j >= n)
break;
pp += st[j];
// Adding to set
z.Add(pp);
}
}
// Converting set into a list
ArrayList fin = new ArrayList();
foreach(string s in z)
{
fin.Add(s);
}
// Sorting the strings int the list
// into lexicographical order
fin.Sort();
// Printing kth substring
Console.Write(fin[k - 1]);
}
// Driver Code
public static void Main(string[] args)
{
string s = "geeksforgeeks";
int k = 5;
int n = s.Length;
kThLexString(s, k, n);
}
}
// This code is contributed by rutvik_56
输出:
eeksf