C++ 基于四叉树实现n*n二维数组的压缩

#include <iostream>
using namespace std;
struct fourTreeNode {
    bool isLeaf;    //是否叶子结点标识符
    int val;        //结点值
    fourTreeNode* children[4];  //指向四个子树的指针

    fourTreeNode(bool leaf, int value) : isLeaf(leaf), val(value) {     //对叶子结点的构造函数
        for (int i = 0; i < 4; i++) {
            children[i] = nullptr;
        }
    }
};
//使用给定二维数组对四叉树进行构建
fourTreeNode* buildTree(int** grid, int x, int y, int size) {   
    //grid:给定二维数组 x,y:标定了当前子区域的起始位置，如整个数组左上角 其对应x y都为0 size:需构建区域大小
    if (size == 1) {    //size为1 即为叶子结点时
        return new fourTreeNode(true, grid[x][y]);  
    }

    fourTreeNode* node = new fourTreeNode(false, 0);    //其他情况则还有需要构建的子结点
    int newSize = size / 2;     //每构建一次 需构建区域大小变为原来一半
   
    node->children[0] = buildTree(grid, x, y, newSize);         
    node->children[1] = buildTree(grid, x, y + newSize, newSize);
    node->children[2] = buildTree(grid, x + newSize, y, newSize);
    node->children[3] = buildTree(grid, x + newSize, y + newSize, newSize);
   //x和y参数会根据当前子区域的位置进行更新。例如，当递归构建左上子区域时，x和y参数保持不变；当递归构建右上子区域时，
   //x保持不变，而y增加了当前子区域的大小，以确定右上子区域在原始二维数组中的位置。

    if (node->children[0]->isLeaf && node->children[1]->isLeaf &&       //当四个孩子结点值相同时合并为同一结点
        node->children[2]->isLeaf && node->children[3]->isLeaf &&
        node->children[0]->val == node->children[1]->val &&
        node->children[0]->val == node->children[2]->val &&
        node->children[0]->val == node->children[3]->val) {
        node->isLeaf = true;
        node->val = node->children[0]->val;
        for (int i = 0; i < 4; i++) {
            delete node->children[i];
            node->children[i] = nullptr;
        }
    }

    return node;
}

void printTree(fourTreeNode* root) {
    if (root == nullptr) {
        return;
    }

    if (root->isLeaf) {
        cout << root->val << " ";
    }
    else {
        cout << "[ ";
        for (int i = 0; i < 4; i++) {
            printTree(root->children[i]);
        }
        cout << "] ";
    }
}

int main() {
    int n;
    cout << "请输入二维数组的大小 n：";
    cin >> n;

    int** grid = new int* [n];
    for (int i = 0; i < n; i++) {
        grid[i] = new int[n];
    }

    cout << "请输入二维数组的元素：" << endl;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            cin >> grid[i][j];
        }
    }

    fourTreeNode* root = buildTree(grid, 0, 0, n);
    cout << "四叉树压缩结果：" << endl;
    printTree(root);
    cout << endl;

    // 释放内存
    for (int i = 0; i < n; i++) {
        delete[] grid[i];
    }
    delete[] grid;

    return 0;
}

代码如上，总体思路同二叉树，难点在于读取二位数组部分的理解，后续更新详细注释~