# Check if a string can be obtained by rotating another string d places

Given two strings str1 and str2 and an integer d, the task is to check whether str2 can be obtained by rotating str1 by d places (either to the left or to the right).

Examples:

Input: str1 = “abcdefg”, str2 = “cdefgab”, d = 2
Output: Yes
Rotate str1 2 places to the left.

Input: str1 = “abcdefg”, str2 = “cdfdawb”, d = 6
Output: No

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: An approach to solve the same problem has been discussed here. In this article, reversal algorithm is used to rotate the string to the left and to the right in O(n). If any one of the rotations of str1 is equal to str2 then print Yes else print No.

Below is the implementation of the above approach:

 `// C++ implementation of the approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function to reverse an array from left ` `// index to right index (both inclusive) ` `void` `ReverseArray(string& arr, ``int` `left, ``int` `right) ` `{ ` `    ``char` `temp; ` `    ``while` `(left < right) { ` `        ``temp = arr[left]; ` `        ``arr[left] = arr[right]; ` `        ``arr[right] = temp; ` `        ``left++; ` `        ``right--; ` `    ``} ` `} ` ` `  `// Function that returns true if str1 can be ` `// made equal to str2 by rotating either ` `// d places to the left or to the right ` `bool` `RotateAndCheck(string& str1, string& str2, ``int` `d) ` `{ ` ` `  `    ``if` `(str1.length() != str2.length()) ` `        ``return` `false``; ` ` `  `    ``// Left Rotation string will contain ` `    ``// the string rotated Anti-Clockwise ` `    ``// Right Rotation string will contain ` `    ``// the string rotated Clockwise ` `    ``string left_rot_str1, right_rot_str1; ` `    ``bool` `left_flag = ``true``, right_flag = ``true``; ` `    ``int` `str1_size = str1.size(); ` ` `  `    ``// Copying the str1 string to left rotation string ` `    ``// and right rotation string ` `    ``for` `(``int` `i = 0; i < str1_size; i++) { ` `        ``left_rot_str1.push_back(str1[i]); ` `        ``right_rot_str1.push_back(str1[i]); ` `    ``} ` ` `  `    ``// Rotating the string d positions to the left ` `    ``ReverseArray(left_rot_str1, 0, d - 1); ` `    ``ReverseArray(left_rot_str1, d, str1_size - 1); ` `    ``ReverseArray(left_rot_str1, 0, str1_size - 1); ` ` `  `    ``// Rotating the string d positions to the right ` `    ``ReverseArray(right_rot_str1, 0, str1_size - d - 1); ` `    ``ReverseArray(right_rot_str1, str1_size - d, str1_size - 1); ` `    ``ReverseArray(right_rot_str1, 0, str1_size - 1); ` ` `  `    ``// Compairing the rotated strings ` `    ``for` `(``int` `i = 0; i < str1_size; i++) { ` ` `  `        ``// If cannot be made equal with left rotation ` `        ``if` `(left_rot_str1[i] != str2[i]) { ` `            ``left_flag = ``false``; ` `        ``} ` ` `  `        ``// If cannot be made equal with right rotation ` `        ``if` `(right_rot_str1[i] != str2[i]) { ` `            ``right_flag = ``false``; ` `        ``} ` `    ``} ` ` `  `    ``// If both or any one of the rotations ` `    ``// of str1 were equal to str2 ` `    ``if` `(left_flag || right_flag) ` `        ``return` `true``; ` `    ``return` `false``; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` ` `  `    ``string str1 = ``"abcdefg"``; ` `    ``string str2 = ``"cdefgab"``; ` ` `  `    ``// d is the rotating factor ` `    ``int` `d = 2; ` ` `  `    ``// In case length of str1 < d ` `    ``d = d % str1.size(); ` ` `  `    ``if` `(RotateAndCheck(str1, str2, d)) ` `        ``cout << ``"Yes"``; ` `    ``else` `        ``cout << ``"No"``; ` ` `  `    ``return` `0; ` `} `

 `# Python3 implementation of the approach  ` ` `  `# Function to reverse an array from left  ` `# index to right index (both inclusive)  ` `def` `ReverseArray(arr, left, right) : ` `     `  `    ``while` `(left < right) : ` `        ``temp ``=` `arr[left];  ` `        ``arr[left] ``=` `arr[right];  ` `        ``arr[right] ``=` `temp;  ` `        ``left ``+``=` `1``;  ` `        ``right ``-``=` `1``;  ` ` `  `# Function that returns true if str1 can be  ` `# made equal to str2 by rotating either  ` `# d places to the left or to the right  ` `def` `RotateAndCheck(str1, str2, d) : ` ` `  `    ``if` `(``len``(str1) !``=` `len``(str2)) : ` `        ``return` `False``;  ` ` `  `    ``# Left Rotation string will contain  ` `    ``# the string rotated Anti-Clockwise  ` `    ``# Right Rotation string will contain  ` `    ``# the string rotated Clockwise  ` `    ``left_rot_str1 ``=` `[]; right_rot_str1 ``=` `[];  ` `    ``left_flag ``=` `True``; right_flag ``=` `True``;  ` `    ``str1_size ``=` `len``(str1);  ` ` `  `    ``# Copying the str1 string to left rotation string  ` `    ``# and right rotation string  ` `    ``for` `i ``in` `range``(str1_size) : ` `        ``left_rot_str1.append(str1[i]);  ` `        ``right_rot_str1.append(str1[i]);  ` ` `  `    ``# Rotating the string d positions to the left  ` `    ``ReverseArray(left_rot_str1, ``0``, d ``-` `1``);  ` `    ``ReverseArray(left_rot_str1, d, str1_size ``-` `1``);  ` `    ``ReverseArray(left_rot_str1, ``0``, str1_size ``-` `1``);  ` ` `  `    ``# Rotating the string d positions to the right  ` `    ``ReverseArray(right_rot_str1, ``0``, str1_size ``-` `d ``-` `1``);  ` `    ``ReverseArray(right_rot_str1,  ` `                 ``str1_size ``-` `d, str1_size ``-` `1``);  ` `    ``ReverseArray(right_rot_str1, ``0``, str1_size ``-` `1``);  ` ` `  `    ``# Compairing the rotated strings  ` `    ``for` `i ``in` `range``(str1_size) : ` ` `  `        ``# If cannot be made equal with left rotation  ` `        ``if` `(left_rot_str1[i] !``=` `str2[i]) :  ` `            ``left_flag ``=` `False``;  ` ` `  `        ``# If cannot be made equal with right rotation  ` `        ``if` `(right_rot_str1[i] !``=` `str2[i]) : ` `            ``right_flag ``=` `False``;  ` ` `  `    ``# If both or any one of the rotations  ` `    ``# of str1 were equal to str2  ` `    ``if` `(left_flag ``or` `right_flag) : ` `        ``return` `True``;  ` `    ``return` `False``;  ` ` `  `# Driver code  ` `if` `__name__ ``=``=` `"__main__"` `:  ` ` `  `    ``str1 ``=` `list``(``"abcdefg"``);  ` `    ``str2 ``=` `list``(``"cdefgab"``);  ` ` `  `    ``# d is the rotating factor  ` `    ``d ``=` `2``;  ` ` `  `    ``# In case length of str1 < d  ` `    ``d ``=` `d ``%` `len``(str1);  ` ` `  `    ``if` `(RotateAndCheck(str1, str2, d)) : ` `        ``print``(``"Yes"``);  ` `    ``else` `: ` `        ``print``(``"No"``);  ` ` `  `# This code is contributed by AnkitRai01 `

Output:
```Yes
```

Time Complexity: O(n)

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Improved By : AnkitRai01

Article Tags :
Practice Tags :