116 lines
3.3 KiB
C++
116 lines
3.3 KiB
C++
#include <iostream>
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#include <climits>
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#include <vector>
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#include <map>
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#include <algorithm>
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struct Maze {
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char data[41][41];
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};
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struct MazeNode {
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MazeNode(std::vector<uint> v, uint priority) : v(v), priority(priority) {}
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std::vector<uint> v;
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uint priority;
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};
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Maze solve_maze(const Maze &maze) {
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Maze result;
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result = maze;
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std::vector<MazeNode> nodes;
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std::make_heap(nodes.begin(), nodes.end(), [](MazeNode n1, MazeNode n2){return n1.priority > n2.priority;});
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nodes.push_back(MazeNode(std::vector<uint>{1, 1}, 0));
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std::push_heap(nodes.begin(), nodes.end(), [](MazeNode n1, MazeNode n2){return n1.priority > n2.priority;});
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std::map<std::vector<uint>, uint> costs;
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std::map<std::vector<uint>, std::vector<uint>> parents;
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costs[std::vector<uint>{1, 1}] = 1;
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while(true) {
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// Get the best node
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MazeNode best = nodes.front();
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std::pop_heap(nodes.begin(), nodes.end(), [](MazeNode n1, MazeNode n2){return n1.priority > n2.priority;});
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nodes.pop_back();
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int current_x = best.v[0];
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int current_y = best.v[1];
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std::vector<uint> here = std::vector<uint>{current_x, current_y};
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// Are we done?
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if (current_x == 39 && current_y == 39) {
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std::vector<uint> parent = here;
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while (true) {
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result.data[parent[1]][parent[0]] = 'o';
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if (parents.find(parent) == parents.end()) break;
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parent = parents[parent];
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}
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return result;
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}
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for (int kernel_y = -1; kernel_y <= 1; kernel_y++) {
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for (int kernel_x = -1; kernel_x <= 1; kernel_x++) {
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// Ignore the current position
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if (kernel_x == 0 && kernel_y == 0) continue;
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uint x = current_x + kernel_x;
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uint y = current_y + kernel_y;
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// Can we go here?
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if (maze.data[y][x] == '#') continue;
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std::vector<uint> next = std::vector<uint>{x, y};
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// The cost is the travelled distance to the next node
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uint cost = costs[here] + abs(kernel_y) + abs(kernel_x);
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// If this node hasn't been added yet or its costs are better, add it!
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if (costs.find(next) == costs.end() || cost < costs[next]) {
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costs[next] = cost;
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uint priority = cost + (39 - x) + (39 - y);
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// Add this node
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nodes.push_back(MazeNode(next, priority));
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std::push_heap(nodes.begin(), nodes.end(), [](MazeNode n1, MazeNode n2){return n1.priority > n2.priority;});
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parents[next] = here;
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}
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}
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}
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}
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return result;
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}
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int main() {
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// Read in the maze
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Maze maze;
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for (int line = 0; line < 41; line++) {
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for (int col = 0; col < 41; col++) {
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maze.data[line][col] = getchar();
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}
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// Read the newline char
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getchar();
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}
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Maze result = solve_maze(maze);
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// Print the result
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for (int line = 0; line < 41; line++) {
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for (int col = 0; col < 41; col++) {
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std::cout << result.data[line][col];
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}
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std::cout << '\n';
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}
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return 0;
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}
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