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hello-algo/en/codes/cpp/chapter_divide_and_conquer/hanota.cpp

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/**
* File: hanota.cpp
* Created Time: 2023-07-17
* Author: krahets (krahets@163.com)
*/
#include "../utils/common.hpp"
/* Move a disc */
void move(vector<int> &src, vector<int> &tar) {
// Take out a disc from the top of src
int pan = src.back();
src.pop_back();
// Place the disc on top of tar
tar.push_back(pan);
}
/* Solve the Tower of Hanoi problem f(i) */
void dfs(int i, vector<int> &src, vector<int> &buf, vector<int> &tar) {
// If only one disc remains on src, move it to tar
if (i == 1) {
move(src, tar);
return;
}
// Subproblem f(i-1): move the top i-1 discs from src with the help of tar to buf
dfs(i - 1, src, tar, buf);
// Subproblem f(1): move the remaining one disc from src to tar
move(src, tar);
// Subproblem f(i-1): move the top i-1 discs from buf with the help of src to tar
dfs(i - 1, buf, src, tar);
}
/* Solve the Tower of Hanoi problem */
void solveHanota(vector<int> &A, vector<int> &B, vector<int> &C) {
int n = A.size();
// Move the top n discs from A with the help of B to C
dfs(n, A, B, C);
}
/* Driver Code */
int main() {
// The tail of the list is the top of the pillar
vector<int> A = {5, 4, 3, 2, 1};
vector<int> B = {};
vector<int> C = {};
cout << "Initial state:\n";
cout << "A =";
printVector(A);
cout << "B =";
printVector(B);
cout << "C =";
printVector(C);
solveHanota(A, B, C);
cout << "After disk movement:\n";
cout << "A =";
printVector(A);
cout << "B =";
printVector(B);
cout << "C =";
printVector(C);
return 0;
}