Given some text lines in one string, each line is separated by ā\nā character. Print the last N lines. If the number of lines is less than N, then print all lines.
An approach for this problem has been already discussed in Set-1 where only 10 lines were printed. In this post, another approach is discussed for printing the last N lines.Ā
Algorithm:
- Split the string around ā\nā using strtok.
- Store the individual strings in a vector.
- Print the last N strings from vector.
Below is the implementation of the above approach:
C++
// C++ program to print the last N lines#include <bits/stdc++.h>using namespace std;Ā
void PrintLast(string s, int t){Ā Ā Ā Ā // Vector to store individual strings.Ā Ā Ā Ā vector<string> v;Ā
Ā Ā Ā Ā // Get a pointer to string.Ā Ā Ā Ā char* str = &s[0];Ā Ā Ā Ā // Split the string around '\n'.Ā Ā Ā Ā char* token = strtok(str, "\n");Ā
Ā Ā Ā Ā // Save all strings in the vector.Ā Ā Ā Ā while (token) {Ā Ā Ā Ā Ā Ā Ā Ā v.push_back(token);Ā Ā Ā Ā Ā Ā Ā Ā token = strtok(NULL, "\n");Ā Ā Ā Ā }Ā
Ā Ā Ā Ā if (v.empty()) {Ā Ā Ā Ā Ā Ā Ā Ā cout << "ERROR: string doesn't contain '\\n' character\n";Ā Ā Ā Ā Ā Ā Ā Ā return;Ā Ā Ā Ā }Ā
Ā Ā Ā Ā // If the string has t linesĀ Ā Ā Ā if (v.size() >= t) {Ā Ā Ā Ā Ā Ā Ā Ā for (int i = v.size() - t; i < v.size(); i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā cout << v[i] << endl;Ā Ā Ā Ā }Ā Ā Ā Ā else {Ā Ā Ā Ā Ā Ā Ā Ā for (int i = 0; i < v.size(); i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā cout << v[i] << endl;Ā Ā Ā Ā }}Ā
// Driver Codeint main(){Ā Ā Ā Ā string s1 = "str1\nstr2\nstr3\nstr4\nstr5\nstr6\nstr7\nstr8\nstr9"Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr10\nstr11\nstr12\nstr13\nstr14\nstr15\nstr16\nstr17"Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr18\nstr19\nstr20\nstr21\nstr22\nstr23\nstr24\nstr25";Ā Ā Ā Ā int n = 10;Ā Ā Ā Ā PrintLast(s1, n);Ā
Ā Ā Ā Ā return 0;} |
Java
// Java program to print the last N linesimport java.util.*;Ā
class GFG {Ā Ā Ā Ā static void printLast(String s, int t)Ā Ā Ā Ā {Ā
Ā Ā Ā Ā Ā Ā Ā Ā // Vector to store individual strings.Ā Ā Ā Ā Ā Ā Ā Ā // Save all strings in the vector.Ā Ā Ā Ā Ā Ā Ā Ā String[] v = s.split("\n");Ā
Ā Ā Ā Ā Ā Ā Ā Ā if (v.length == 0) Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā System.out.println("ERROR: string doesn't " + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "contain '\\n' character");Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā return;Ā Ā Ā Ā Ā Ā Ā Ā }Ā
Ā Ā Ā Ā Ā Ā Ā Ā // If the string has t linesĀ Ā Ā Ā Ā Ā Ā Ā if (v.length >= t) Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā for (int i = v.length - t; i < v.length; i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā System.out.println(v[i]);Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā }Ā Ā Ā Ā Ā Ā Ā Ā } Ā Ā Ā Ā Ā Ā Ā Ā elseĀ Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā for (int i = 0; i < v.length; i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā System.out.println(v[i]);Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā }Ā Ā Ā Ā Ā Ā Ā Ā }Ā Ā Ā Ā }Ā
Ā Ā Ā Ā // Driver CodeĀ Ā Ā Ā public static void main(String[] args) Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā String s1 = "str1\nstr2\nstr3\nstr4\nstr5\nstr6\nstr7" + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr8\nstr9\nstr10\nstr11\nstr12\nstr13" + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr14\nstr15\nstr16\nstr17\nstr18\nstr19" + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr20\nstr21\nstr22\nstr23\nstr24\nstr25";Ā Ā Ā Ā Ā Ā Ā Ā int n = 10;Ā Ā Ā Ā Ā Ā Ā Ā printLast(s1, n);Ā Ā Ā Ā }}Ā
// This code is contributed by// sanjeev2552 |
Python3
# Python3 program to print the last N lines def PrintLast(s, t): Ā
Ā Ā Ā Ā # Vector to store individual strings. Ā Ā Ā Ā v = s.split('\n')Ā Ā Ā Ā Ā Ā Ā Ā Ā if len(v) == 0: Ā Ā Ā Ā Ā Ā Ā Ā print("ERROR: string doesn't ",Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "contain '\\n' character\n") Ā Ā Ā Ā Ā Ā Ā Ā returnĀ Ā Ā Ā Ā Ā Ā Ā Ā # If the string has t lines Ā Ā Ā Ā elif len(v) >= t: Ā Ā Ā Ā Ā Ā Ā Ā for i in range(len(v) - t, len(v)): Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā print(v[i]) Ā Ā Ā Ā Ā Ā Ā Ā Ā else:Ā Ā Ā Ā Ā Ā Ā Ā for i in range(0, len(v)): Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā print(v[i])Ā Ā Ā Ā Ā # Driver Code if __name__ == "__main__":Ā
Ā Ā Ā Ā s1 = "str1\nstr2\nstr3\nstr4\nstr5\nstr6" + \Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr7\nstr8\nstr9\nstr10\nstr11" + \Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr12\nstr13\nstr14\nstr15\nstr16" + \Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr17\nstr18\nstr19\nstr20\nstr21" + \Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr22\nstr23\nstr24\nstr25"Ā Ā Ā Ā Ā Ā Ā Ā Ā n = 10Ā Ā Ā Ā PrintLast(s1, n) Ā
# This code is contributed by Rituraj Jain |
C#
// C# program to print the last N linesusing System;Ā
class GFG {Ā Ā Ā Ā static void printLast(String s, int t)Ā Ā Ā Ā {Ā
Ā Ā Ā Ā Ā Ā Ā Ā // List to store individual strings.Ā Ā Ā Ā Ā Ā Ā Ā // Save all strings in the vector.Ā Ā Ā Ā Ā Ā Ā Ā String[] v = s.Split('\n');Ā
Ā Ā Ā Ā Ā Ā Ā Ā if (v.Length == 0) Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Console.WriteLine("ERROR: string doesn't " + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "contain '\\n' character");Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā return;Ā Ā Ā Ā Ā Ā Ā Ā }Ā
Ā Ā Ā Ā Ā Ā Ā Ā // If the string has t linesĀ Ā Ā Ā Ā Ā Ā Ā if (v.Length >= t) Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā for (int i = v.Length - t; i < v.Length; i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Console.WriteLine(v[i]);Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā }Ā Ā Ā Ā Ā Ā Ā Ā } Ā Ā Ā Ā Ā Ā Ā Ā elseĀ Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā for (int i = 0; i < v.Length; i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Console.WriteLine(v[i]);Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā }Ā Ā Ā Ā Ā Ā Ā Ā }Ā Ā Ā Ā }Ā
Ā Ā Ā Ā // Driver CodeĀ Ā Ā Ā public static void Main(String[] args) Ā Ā Ā Ā {Ā Ā Ā Ā Ā Ā Ā Ā String s1 = "str1\nstr2\nstr3\nstr4\nstr5\nstr6\nstr7" + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr8\nstr9\nstr10\nstr11\nstr12\nstr13" + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr14\nstr15\nstr16\nstr17\nstr18\nstr19" + Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā "\nstr20\nstr21\nstr22\nstr23\nstr24\nstr25";Ā Ā Ā Ā Ā Ā Ā Ā int n = 10;Ā Ā Ā Ā Ā Ā Ā Ā printLast(s1, n);Ā Ā Ā Ā }}Ā
// This code is contributed by Rajput-Ji |
Javascript
function PrintLast( s, t){Ā Ā Ā Ā Ā Ā Ā Ā Ā const v = s.split("\n");Ā Ā Ā Ā if (v.length==0) {Ā Ā Ā Ā Ā Ā Ā Ā console.log( "ERROR: string doesn't contain '\\n' character\n");Ā Ā Ā Ā Ā Ā Ā Ā return;Ā Ā Ā Ā }Ā
Ā Ā Ā Ā // If the string has t linesĀ Ā Ā Ā if (v.length >= t) {Ā Ā Ā Ā Ā Ā Ā Ā for (let i = v.length - t; i < v.length; i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā console.log(v[i]);Ā Ā Ā Ā }Ā Ā Ā Ā else {Ā Ā Ā Ā Ā Ā Ā Ā for (let i = 0; i < v.length; i++)Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā Ā console.log(v[i]);Ā Ā Ā Ā }}Ā
Ā Ā Ā Ā let s1 = "str1\nstr2\nstr3\nstr4\nstr5\nstr6\nstr7\nstr8\nstr9\nstr10\nstr11\nstr12\nstr13\nstr14\nstr15\nstr16\nstr17\nstr18\nstr19\nstr20\nstr21\nstr22\nstr23\nstr24\nstr25";Ā Ā Ā Ā let n = 10;Ā Ā Ā Ā PrintLast(s1, n);Ā
Ā Ā Ā Ā // This code is contributed by garg28harsh. |
Output
str16 str17 str18 str19 str20 str21 str22 str23 str24 str25
Time Complexity: O(n)
Auxiliary Space: O(n)
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