Hanoi Tower

hanoi.cpp

#include <stdio.h>

struct stack {
  int v[100];
  int top;
} stacks[3];

int N;

void push(struct stack * a, int v) {
  (*a).v[(*a).top++] = v;
}

int pop(struct stack * a) {
  return (*a).v[((*a).top--)-1];
}

void printblock(int value) {
  for (int i=0; i<N-value; ++i) printf(" ");
  for (int i=0; i<value; ++i) printf("=");
  for (int i=0; i<value; ++i) printf("=");
  for (int i=0; i<N-value; ++i) printf(" ");
}

void printline(int idx) {
  printf("|");

  for (int i=0; i<3; ++i) {
    if (idx < stacks[i].top)
      printblock(stacks[i].v[idx]);
    else
      printblock(0);
    printf("|");
  }

  printf("\n");
}

void print() {
  for (int i=N-1; i>=0; i--)
    printline(i);
  for (int i=0; i<N*2*3 + 4; ++i) printf("-");
  printf("\n");
}

void hanoi(int N, struct stack * a, struct stack * b, struct stack * c) {
  if (N > 0) {
    hanoi(N-1, a, c, b);
    push(c, pop(a));
    print();
    hanoi(N-1, b, a, c);
  }
}

int main() {
  scanf("%d", &N);

  for (int i=0; i<N; ++i) {
     push(stacks, N-i);
  }
  print();
  hanoi(N, &stacks[0], &stacks[1], &stacks[2]);
}

/*
For example, N=3:
|  ==  |      |      |
| ==== |      |      |
|======|      |      |
----------------------
|      |      |      |
| ==== |      |      |
|======|      |  ==  |
----------------------
|      |      |      |
|      |      |      |
|======| ==== |  ==  |
----------------------
|      |      |      |
|      |  ==  |      |
|======| ==== |      |
----------------------
|      |      |      |
|      |  ==  |      |
|      | ==== |======|
----------------------
|      |      |      |
|      |      |      |
|  ==  | ==== |======|
----------------------
|      |      |      |
|      |      | ==== |
|  ==  |      |======|
----------------------
|      |      |  ==  |
|      |      | ==== |
|      |      |======|
----------------------
*/