C++ Coding Test Course, Game Development

Hello everyone! Today, we will discuss an algorithm problem related to game development in a course designed to prepare for C++ coding tests. This article will present algorithm problems necessary for game development and explain the process of solving those problems in detail. This course is intended for job seekers using C++, as well as anyone interested in game development.

Problem Description

Problem: Maze Escape

You need to find a way from the starting point (0, 0) to the destination (N-1, M-1) in a 2D maze. The maze is represented as an array of 0s and 1s, where 0 indicates a path and 1 indicates a wall. You can only move up, down, left, and right, and you need to write a program to find the minimum distance to reach the destination.

Input Format

The first line contains two integers, N and M. (1 ≤ N, M ≤ 100)
The next N lines contain M integers that form an array of 0s and 1s.

Output Format

Print the minimum distance from the starting point to the destination (length of the path). Print -1 if it is not reachable.

Example Input

Example Output

Problem Solving Process

1. Problem Analysis

The given problem can be solved using either DFS (Depth First Search) or BFS (Breadth First Search) algorithms. Since we are looking for the shortest distance, it is appropriate to use BFS. BFS explores all adjacent nodes from the current position using a queue and guarantees the shortest path.

2. Algorithm Design

The BFS algorithm to be implemented follows these steps:

Start at the starting point (0, 0) and enqueue the position and the current distance (0).
Dequeue the front element from the queue and check if that position matches the destination (target).
If it matches, return the distance up to that point.
If it does not match, add all valid adjacent positions (up, down, left, right) to the queue. Valid positions are those that do not go out of bounds and are 0.
Search all possible paths and return -1 if the destination cannot be reached.

3. C++ Code Implementation

Now let’s implement the above algorithm in C++:

#include <iostream>
#include <queue>
#include <vector>

using namespace std;

int N, M;
vector<vector<int>> maze;
vector<vector<bool>> visited;

int bfs()
{
    queue<pair<int, int>> q;
    q.push(make_pair(0, 0));
    visited[0][0] = true;
    int distance[4][2] = { {0,1}, {1,0}, {0,-1}, {-1,0} }; // Right, Down, Left, Up
    int steps = 0;

    while (!q.empty())
    {
        int sz = q.size();
        for (int i = 0; i < sz; i++)
        {
            int x = q.front().first;
            int y = q.front().second;
            q.pop();

            // If we have reached the destination
            if (x == N - 1 && y == M - 1)
                return steps;

            for (int j = 0; j < 4; j++)
            {
                int nx = x + distance[j][0];
                int ny = y + distance[j][1];

                if (nx >= 0 && nx < N && ny >= 0 && ny < M && maze[nx][ny] == 0 && !visited[nx][ny])
                {
                    visited[nx][ny] = true;
                    q.push(make_pair(nx, ny));
                }
            }
        }
        steps++;
    }

    return -1; // If it cannot be reached
}

int main()
{
    cin >> N >> M;
    maze.resize(N, vector<int>(M));
    visited.resize(N, vector<bool>(M, false));

    for (int i = 0; i < N; i++)
        for (int j = 0; j < M; j++)
            cin >> maze[i][j];

    int result = bfs();
    cout << result << endl;

    return 0;
}

4. Code Explanation

The first thing set in the code is the two-dimensional vector for storing the size and contents of the maze. Then, within the BFS function, we start exploring from the starting point using a queue. At each step, we check all possible spaces to move up, down, left, and right, enqueuing them, and if we find the destination, we return the distance up to that point. Finally, in the main function, we call the implemented BFS function to output the result based on the input.

Testing and Validation

Now we will test the implemented code. We need to ensure that the results come out correctly through various test cases.

Test Cases

Test Case 1:

Expected Output: 4

Test Case 2:

Expected Output: 4

Test Case 3:

        2 2
        1 1
        1 1

Expected Output: -1 (Impossible to move)

Feedback and Continuous Improvement

This algorithm problem provides useful skills for solving various maze or pathfinding related problems in game development. It can be expanded to topics like generating more complex mazes, path optimization, or AI for enemies. Continuous practice and solving diverse problems are important to improve skills.

Conclusion

Today, we dealt with an algorithm problem related to game development as part of C++ coding tests. Through a simple example of the maze escape problem, we applied the BFS algorithm and learned how to search for the shortest path. The direction for the future is to expand to more complex problems based on these basic algorithms.

Through the content so far, I hope you have had the opportunity to build your algorithm and problem-solving skills, and also to apply those skills in game development.

In the next session, let’s delve deeper into algorithms with more diverse problems. Thank you!