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Add C++ code for Flood Fill algorithm
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‎CONTRIBUTORS.md

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@@ -59,3 +59,4 @@ This file lists everyone, who contributed to this repo and wanted to show up her
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- Mahdi Sarikhani
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- Ridham177
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- Hugo Salou
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- Dimitri Belopopsky

‎contents/flood_fill/code/cpp/flood_fill.cpp

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#include <array>
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#include <cassert>
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#include <iostream>
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#include <queue>
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#include <stack>
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#include <vector>
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using CartesianIndex = std::array<int, 2>;
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auto inbounds(CartesianIndex size, CartesianIndex loc) {
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if (loc[0] < 0 || loc[1] < 0) {
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return false;
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} else if (loc[0] >= size[0] || loc[1] >= size[1]) {
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return false;
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}
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return true;
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}
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auto find_neighbors(
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std::vector<std::vector<float>> const& grid,
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CartesianIndex loc,
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float old_value,
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float /* new_value */) {
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std::vector<CartesianIndex> possible_neighbors{
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{loc[0], loc[1] + 1},
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{loc[0] + 1, loc[1]},
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{loc[0], loc[1] - 1},
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{loc[0] - 1, loc[1]}};
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std::vector<CartesianIndex> neighbors;
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for (auto possible_neighbor : possible_neighbors) {
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auto size = CartesianIndex{
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static_cast<int>(grid[0].size()), static_cast<int>(grid.size())};
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auto x = static_cast<std::size_t>(possible_neighbor[0]);
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auto y = static_cast<std::size_t>(possible_neighbor[1]);
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if (inbounds(size, possible_neighbor) && grid[x][y] == old_value) {
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neighbors.push_back(possible_neighbor);
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}
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}
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return neighbors;
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}
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void recursive_fill(
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std::vector<std::vector<float>>& grid,
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CartesianIndex loc,
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float old_value,
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float new_value) {
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if (old_value == new_value) {
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return;
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}
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auto x = static_cast<std::size_t>(loc[0]);
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auto y = static_cast<std::size_t>(loc[1]);
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grid[x][y] = new_value;
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auto possible_neighbors = find_neighbors(grid, loc, old_value, new_value);
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for (auto possible_neighbor : possible_neighbors) {
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recursive_fill(grid, possible_neighbor, old_value, new_value);
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}
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}
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void queue_fill(
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std::vector<std::vector<float>>& grid,
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CartesianIndex loc,
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float old_value,
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float new_value) {
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if (old_value == new_value) {
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return;
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}
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auto q = std::queue<CartesianIndex>{};
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q.push(loc);
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auto x = static_cast<std::size_t>(loc[0]);
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auto y = static_cast<std::size_t>(loc[1]);
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grid[x][y] = new_value;
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while (q.size() > 0) {
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auto current_loc = q.front();
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q.pop();
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auto possible_neighbors =
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find_neighbors(grid, current_loc, old_value, new_value);
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for (auto neighbor : possible_neighbors) {
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auto neighbor_x = static_cast<std::size_t>(neighbor[0]);
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auto neighbor_y = static_cast<std::size_t>(neighbor[1]);
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grid[neighbor_x][neighbor_y] = new_value;
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q.push(neighbor);
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}
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}
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}
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void stack_fill(
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std::vector<std::vector<float>>& grid,
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CartesianIndex loc,
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float old_value,
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float new_value) {
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if (old_value == new_value) {
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return;
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}
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auto s = std::stack<CartesianIndex>{};
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s.push(loc);
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while (s.size() > 0) {
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auto current_loc = s.top();
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s.pop();
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auto x = static_cast<std::size_t>(current_loc[0]);
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auto y = static_cast<std::size_t>(current_loc[1]);
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if (grid[x][y] == old_value) {
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grid[x][y] = new_value;
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auto possible_neighbors =
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find_neighbors(grid, current_loc, old_value, new_value);
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for (auto neighbor : possible_neighbors) {
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s.push(neighbor);
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}
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}
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}
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}
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int main() {
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std::vector<std::vector<float>> grid{
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{0, 0, 1, 0, 0},
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{0, 0, 1, 0, 0},
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{0, 0, 1, 0, 0},
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{0, 0, 1, 0, 0},
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{0, 0, 1, 0, 0}};
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std::vector<std::vector<float>> solution_grid{
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{1, 1, 1, 0, 0},
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{1, 1, 1, 0, 0},
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{1, 1, 1, 0, 0},
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{1, 1, 1, 0, 0},
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{1, 1, 1, 0, 0}};
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CartesianIndex start_loc{1, 1};
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auto test_grid = grid;
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recursive_fill(test_grid, start_loc, 0.0, 1.0);
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assert(test_grid == solution_grid);
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test_grid = grid;
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queue_fill(test_grid, start_loc, 0.0, 1.0);
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assert(test_grid == solution_grid);
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test_grid = grid;
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stack_fill(test_grid, start_loc, 0.0, 1.0);
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assert(test_grid == solution_grid);
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return EXIT_SUCCESS;
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}

‎contents/flood_fill/flood_fill.md

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@@ -90,6 +90,8 @@ In code, this might look like this:
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[import:23-41, lang:"julia"](code/julia/flood_fill.jl)
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{% sample lang="c" %}
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[import:28-46, lang:"c"](code/c/flood_fill.c)
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{% sample lang="cpp" %}
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[import:18-42, lang:"cpp"](code/cpp/flood_fill.cpp)
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{% sample lang="py" %}
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[import:10-25, lang="python"](code/python/flood_fill.py)
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{% sample lang="coco" %}
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[import:92-104, lang:"julia"](code/julia/flood_fill.jl)
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{% sample lang="c" %}
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[import:174-189, lang:"c"](code/c/flood_fill.c)
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{% sample lang="cpp" %}
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[import:44-59, lang:"cpp"](code/cpp/flood_fill.cpp)
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{% sample lang="py" %}
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[import:55-63, lang="python"](code/python/flood_fill.py)
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{% sample lang="coco" %}
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[import:43-63, lang:"julia"](code/julia/flood_fill.jl)
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{% sample lang="c" %}
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[import:79-102, lang:"c"](code/c/flood_fill.c)
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{% sample lang="cpp" %}
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[import:87-111, lang:"cpp"](code/cpp/flood_fill.cpp)
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{% sample lang="py" %}
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[import:27-36, lang="python"](code/python/flood_fill.py)
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{% sample lang="coco" %}
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[import:66-90, lang:"julia"](code/julia/flood_fill.jl)
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{% sample lang="c" %}
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[import:149-172, lang:"c"](code/c/flood_fill.c)
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{% sample lang="cpp" %}
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[import:61-85, lang:"cpp"](code/cpp/flood_fill.cpp)
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{% sample lang="py" %}
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[import:38-53, lang="python"](code/python/flood_fill.py)
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{% sample lang="coco" %}
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[import, lang:"julia"](code/julia/flood_fill.jl)
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{% sample lang="c" %}
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[import, lang:"c"](code/c/flood_fill.c)
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{% sample lang="cpp" %}
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[import, lang:"cpp"](code/cpp/flood_fill.cpp)
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{% sample lang="py" %}
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[import:, lang="python"](code/python/flood_fill.py)
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{% sample lang="coco" %}

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