Question

How to shift letters in a string x times by giving an array of shifts in C

Answer 1

#include <stdio.h>
#include <string.h>

/*

string = "aaa"
After Shifting the first 1 letter by 1 = "baa"
After shifting the first 2 letters by 2 = "dca"
After shifting the first 3 letters 3 = "gfd"
result = "gfd"

*/

char* shifLetters(char* str, int* shifts, int size) {
    for (int i = size - 1; i >= 0; i--) {
        if (i + 1 < size) {
            shifts[i] += shifts[i + 1];
        }
        shifts[i] = shifts[i] % 26;
        int asciicode = str[i] - 'a';
        asciicode = asciicode + shifts[i];
        if (asciicode > 25) {
            asciicode = asciicode - 26;
        }
        str[i] = (char)('a' + asciicode);
    }
    
    return str;
}

int main() {
    char str[] = "aaa";
    int shifts[] = {1, 2, 3};
    int size = strlen(str);
    
    shifLetters(str, shifts, size);
    
    printf("%s", str);
    
    return 0;
}


 
 
/*
run:
 
gfd
 
*/

 

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