quadtree_create.cpp

Node* createTree(vector<vector<int>>& matrix, int row1, int row2, int col1, int col2)
{
    if(row1 > row2 || col1 > col2)return nullptr;
    if(row1 == row2 && col1 == col2)return new Node(matrix[row1][col1]);
    int rMid = row1 + (row2 - row1) / 2, cMid = col1 + (col2 - col1) / 2;
    auto topL = createTree(matrix, row1, rMid, col1, cMid);
    auto topR = createTree(matrix, row1, rMid, cMid + 1, col2); 
    auto botL = createTree(matrix, rMid + 1, row2, col1, cMid);
    auto botR = createTree(matrix, rMid + 1, row2, cMid + 1, col2);
    Node* node = new Node(val(topL) + val(topR) + val(botL) + val(botR));
    node->children[0] = topL;
    node->children[1] = topR;
    node->children[2] = botL;
    node->children[3] = botR;
    return node;
}