Three ways to implement left-spin string in C language

Updated: March 21, 2024 09:57:33 Author: Li Bai

This article will use three ideas to achieve the string left rotation (circular movement, interception and splicing, reverse inversion), the article through the code examples and graphic introduction is very detailed, has a certain reference value, the need of friends can refer to the next

Title:

Implement a function that can left-spin k characters in a string.

For example: ABCD left one character to obtain BCDA ABCD left two characters to obtain CDAB

Method 1:

Let's draw a picture and analyze it:

Basic logic:

That is, before each rotation, we take the first element of the arr array and store it in tmp, then we move every remaining element of the arr array one bit forward, and finally we put the element in tmp back to the end of the arr array.

Implementation algorithm:

We find that when abcd rotates k = 4 characters by 4 characters, the array returns to its own array abcd. Now, we can think of it this way, even though we rotated 4 characters, we actually rotated 0 characters; And so on, by rotating 5 characters, you actually rotate 1 character; And so it goes on...... Next, we lengthen the character length to abcde 5 characters, rotate k = 5 characters, the array will return to its own array abcde, and the following analysis is the same as the 4 character analysis. Then, we can get the expression num(actual number of counts) = k % len(number of array characters).

Code implementation:

#include <stdio.h> #include <string.h> void Turn_left(char arr[],int k) { int len = strlen(arr); // Find the true number of rotations int num = k % len; for (int i = 0; i < num; i++) {// Move one char tmp = arr[0]; int j = 0; for (j = 0; j < len - 1; j++) {// Mobile data arr[j] = arr[j + 1]; } arr[j] = tmp; } } int main() { char arr[] = "abcd"; int k = 0; scanf("%d", &k); // Enter the number of rotating characters Turn_left(arr, k); printf("%s\n", arr); return 0; }

Running result:

Method 2:

We can also draw a picture to analyze:

Here we are going to use two functions:

strcpy() // String copy strcpy(str1,str2)// Copies the elements of str2 into str2 strncat()// This is also string copy strncat(tmp,arr,k)// Copies the elements from arr to the end of the string tmp, Copy k

Code implementation:

#include <stdio.h> #include <string.h> void Turn_left(char arr[], int k) { int len = strlen(arr); int num = k % len; char tmp[1000] = { 0 }; // Copy the string from arr + num to strcpy(tmp, arr + num); // Copy the element at the beginning of arr to the end of the string tmp, copying num strncat(tmp, arr, num); // Finally copy the entire tmp array element into the arr array strcpy(arr, tmp); } int main() { char arr[] = "abcd"; int k = 0; scanf("%d", &k); // Enter the number of rotating characters Turn_left(arr, k); //2 printf("%s\n", arr); return 0; }

Running result:

Method 3:

Finally, let's draw a picture and analyze it:

Code implementation:

#include <stdio.h> void Reverse(char arr[], int i, int j) { while (i < j) { char tmp = arr[i]; arr[i] = arr[j]; arr[j] = tmp; i++; j--; } } void Turn_left(char arr[], int k) { int len = strlen(arr); int num = k % len; // Reverse the element before the num position (arr, 0, num-1); // Reverse the num position and the elements following it (arr, num, len-1); // The entire array is in Reverse order (arr, 0, len-1); } int main() { char arr[] = "abcd"; int k = 0; scanf("%d", &k); // Enter the number of rotating characters Turn_left(arr, k); //2 printf("%s\n", arr); return 0; }

Running result:

The above is the details of the three ways to implement left-handed strings in C language, more information about left-handed strings in C language please pay attention to other related articles in Script home!

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