/* inc, x2,x3 calculator */
#include <stdio.h>
#include <stdlib.h>
/* actions enum */
enum {
    INC,
    X2,
    X3
} ctions;

/* step list item */
typedef struct calcFlow{
    short int action;
    struct calcFlow* prev;
}calcFlow;

/* create step & allocate it with previes step */
struct calcFlow* createNewStep(short int action, struct calcFlow* prev)  {
    struct calcFlow *step;
    step = (struct calcFlow*) malloc (sizeof(calcFlow));
    if (step != NULL) {
        step->prev = prev;
        step->action = action;
    }
    return step;
}



/* get valid incoming integer */
int getSource(void) {
    int value=0;
    do{
        printf("%s", "Input positive integer: ");
        scanf("%6d", &value);
    } while ( (value <= 0) );
    return value;
}

/* actionHandler */
int executeAction(int src,int action) {
    switch (action) {
        case INC:
            printf ("increment \t%d\n", ++src);
            break;
        case X2:
            src*=2;
            printf("multiply x2 \t%d\n", src);
            break;
        case X3:
            src*=3;
            printf("multiply x3 \t%d\n", src);
            break;
    }
    return src;
}



int main (int argc, char **argv) {
    int source, reverse=0, stepNumber=1;
    source=getSource();
    printf("Source is %d\n", source);

    struct calcFlow *currentStep=NULL, *prev=NULL;

/* calculate */
    while (source >0) {
//      printf("%d\n", source);
        if (source%3==0) {
            currentStep = createNewStep(X3,currentStep);
            source/=3;
        } else
        if (source%2==0) {
            currentStep = createNewStep(X2,currentStep);
            source /=2;
        }  else
        {
            currentStep = createNewStep(INC,currentStep);
            source--;
        }
    }
/* reverse */
    do {
        printf("step \t#%d\t",stepNumber++);
        prev=currentStep->prev;
        switch (currentStep->action) {
            case INC:
            case X2:
            case X3:  reverse = executeAction( reverse, currentStep->action ); break;
            default: printf("unknown action %d", currentStep->action);

        }
        free(currentStep);
        currentStep=prev;
    } while (currentStep!= NULL );


    return 0;
}