Implemented block movement algorithm in C language

Environment used for learning

ideone.com (https://ideone.com/)
A site where you can learn programming online

Reference material

Latest algorithm dictionary in C language (written by Haruhiko Okumura / 1991 first edition Gijutsu-Hyoronsha: 249 pages)

Overview of block movement algorithm

It is an algorithm that replaces blocks in a character string.

(The following is quoted from the reference material)

If you move block 12345 after block abcd in an editor instruction, eg text xyz12345abcdefg, you get xyzabcd12345efg. This operation is also to swap 12345 and abcd, or to rotate 12345abcd to the right by 4 characters.

This time, we implemented the process to change the character string "PROGRAMMING PRINCIPLES" consisting of two words "PROGRAMMING" and "PRINCIPLES" into "PRINCIPLES PROGRAMMING" by exchanging the words.

Source code

`moveblock.c`


/*Block move block move*/

#include <stdio.h>
#include <stdlib.h>

char sentense[] = "PROGRAMMINGPRINCIPLES";

int main(void) {
	printf("%s\n",sentense);
	//Call the string move function
	rotate(0, 10, 20);	
	printf("%s\n", sentense);

	return EXIT_SUCCESS;
}

//String inversion function
//If the string length is odd, only the center character is not inverted
void reverse(int i,int j){
	//Tmp variable to replace
	int t;
	while(i < j){
		t = sentense[i];
		sentense[i] = sentense[j];
		sentense[j] = t;
		
		//Shift the position of the character string to be processed one by one
		i++;
		j--;
		
		printf("%s i=%d j=%d (reverse)\n", sentense, i, j);
	}
}

//String movement function
//Call the reverse function
//First argument: Start position of the left part of the character string to be replaced
//Second argument: Start position of the right part of the character string to be replaced
//Third argument: The entire character string to be replaced
void rotate(int left, int mid, int right){
	reverse(left, mid);
	reverse(mid + 1,right);
	reverse(left, right);
}

Execution result

The result was as expected.

`result.txt(Any)`


Success #stdin #stdout 0s 4488KB

PROGRAMMINGPRINCIPLES
GROGRAMMINPPRINCIPLES i=1 j=9 (reverse)
GNOGRAMMIRPPRINCIPLES i=2 j=8 (reverse)
GNIGRAMMORPPRINCIPLES i=3 j=7 (reverse)
GNIMRAMGORPPRINCIPLES i=4 j=6 (reverse)
GNIMMARGORPPRINCIPLES i=5 j=5 (reverse)
GNIMMARGORPSRINCIPLEP i=12 j=19 (reverse)
GNIMMARGORPSEINCIPLRP i=13 j=18 (reverse)
GNIMMARGORPSELNCIPIRP i=14 j=17 (reverse)
GNIMMARGORPSELPCINIRP i=15 j=16 (reverse)
GNIMMARGORPSELPICNIRP i=16 j=15 (reverse)
PNIMMARGORPSELPICNIRG i=1 j=19 (reverse)
PRIMMARGORPSELPICNING i=2 j=18 (reverse)
PRIMMARGORPSELPICNING i=3 j=17 (reverse)
PRINMARGORPSELPICMING i=4 j=16 (reverse)
PRINCARGORPSELPIMMING i=5 j=15 (reverse)
PRINCIRGORPSELPAMMING i=6 j=14 (reverse)
PRINCIPGORPSELRAMMING i=7 j=13 (reverse)
PRINCIPLORPSEGRAMMING i=8 j=12 (reverse)
PRINCIPLERPSOGRAMMING i=9 j=11 (reverse)
PRINCIPLESPROGRAMMING i=10 j=10 (reverse)
PRINCIPLESPROGRAMMING

Impressions

Ideone.com as a programming learning environment is very easy to use. If you investigate how to use it, it seems more likely, so it will be an issue for the future.
After all, it is easier to understand if you write and move it.
Assuming that this algorithm is actually incorporated into the product code, it seems that some modifications will be required. (From the point of view of how to edit the character string of a global variable.)

[C language algorithm] Block movement