Given an input string, write a function that returns the Run Length Encoded string for the input string.
For example, if the input string is “wwwwaaadexxxxxx”, then the function should return “w4a3d1e1x6”
Follow the steps below to solve this problem:
- Pick the first character from the source string.
- Append the picked character to the destination string.
- Count the number of subsequent occurrences of the picked character and append the count to the destination string.
- Pick the next character and repeat steps 2, 3 and 4 if the end of the string is NOT reached.
Below is the implementation of the above approach:
C++
// CPP program to implement run length encoding#include <bits/stdc++.h>using namespace std;void printRLE(string str){ int n = str.length(); for (int i = 0; i < n; i++) { // Count occurrences of current character int count = 1; while (i < n - 1 && str[i] == str[i + 1]) { count++; i++; } // Print character and its count cout << str[i] << count; }}//Driver codeint main(){ string str = "wwwwaaadexxxxxxywww"; printRLE(str); return 0;} |
C
#include <stdio.h>#include <stdlib.h>#include <string.h>#define MAX_RLEN 50/* Returns the Run Length Encoded string for the source string src */char* encode(char* src){ int rLen; char count[MAX_RLEN]; int len = strlen(src); /* If all characters in the source string are different, then size of destination string would be twice of input string. For example if the src is "abcd", then dest would be "a1b1c1d1" For other inputs, size would be less than twice. */ char* dest = (char*)malloc(sizeof(char) * (len * 2 + 1)); int i, j = 0, k; /* traverse the input string one by one */ for (i = 0; i < len; i++) { /* Copy the first occurrence of the new character */ dest[j++] = src[i]; /* Count the number of occurrences of the new character */ rLen = 1; while (i + 1 < len && src[i] == src[i + 1]) { rLen++; i++; } /* Store rLen in a character array count[] */ sprintf(count, "%d", rLen); /* Copy the count[] to destination */ for (k = 0; *(count + k); k++, j++) { dest[j] = count[k]; } } /*terminate the destination string */ dest[j] = '\0'; return dest;}/*driver program to test above function */int main(){ char str[] = "wwwwaaadexxxxxxywww"; char* res = encode(str); printf("%s", res); getchar();} |
Java
/*package whatever //do not write package name here */import java.io.*;public class GFG { public static void encoding(String str) { int n = str.length(); for (int i = 0; i < n; i++) { // Count occurrences of current character int count = 1; while (i < n - 1 && str.charAt(i) == str.charAt(i + 1)) { count++; i++; } // Print character and its count System.out.print(str.charAt(i) + "" + count); } } // Driver code public static void main(String[] args) { String str = "wwwwaaadexxxxxxywww"; encoding(str); }} |
Python3
# Python3 program to implement # run length encodingdef printRLE(st): n = len(st) i = 0 while i < n- 1: # Count occurrences of # current character count = 1 while (i < n - 1 and st[i] == st[i + 1]): count += 1 i += 1 i += 1 # Print character and its count print(st[i - 1] + str(count), end = "")# Driver code if __name__ == "__main__": st = "wwwwaaadexxxxxxywww" printRLE(st)# This code is contributed by Chitranayal |
C#
// C# program to implement run length encodingusing System;class GFG{public class RunLength_Encoding { public static void printRLE(String str) { int n = str.Length; for (int i = 0; i < n; i++) { // Count occurrences of current character int count = 1; while (i < n - 1 && str[i] == str[i + 1]) { count++; i++; } // Print character and its count Console.Write(str[i]); Console.Write(count); } } public static void Main(String[] args) { String str = "wwwwaaadexxxxxxywww"; printRLE(str); }}}// This code is contributed by shivanisinghss2110 |
Javascript
<script>// Javascript program to implement run length encoding function printRLE(str) { let n = str.length; for (let i = 0; i < n; i++) { // Count occurrences of current character let count = 1; while (i < n - 1 && str[i] == str[i+1]) { count++; i++; } // Print character and its count document.write(str[i]); document.write(count); } } let str = "wwwwaaadexxxxxxywww"; printRLE(str); // This code is contributed by rag2127</script> |
Output
w4a3d1e1x6y1w3
Time Complexity: O(n)
Auxiliary Space: O(1)
Please write comments if you find the above code/algorithm incorrect, or find better ways to solve the same problem.
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