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Advent2022/Day9/part1.cpp

94 lines
2.0 KiB
C++

#include <iostream>
#include <string>
#include <set>
#include <utility>
using namespace std;
struct Rope
{
Rope(pair<int, int> head, pair<int, int> tail) : head{head}, tail{tail} {}
pair<int, int> head, tail;
};
Rope move_rope(Rope rope, int dx, int dy);
int main(int argc, char* argv[])
{
Rope rope({0,0}, {0,0});
set<pair<int, int>> visited;
string line;
while(getline(cin, line))
{
char dir = line[0];
int amount = stoi(line.substr(2));
int dx = (dir=='R')?1:((dir=='L')?-1:0);
int dy = (dir=='U')?1:((dir=='D')?-1:0);
for(int i = 0; i < amount; i++)
{
rope = move_rope(rope, dx, dy);
visited.insert(rope.tail);
}
}
cout << visited.size() << endl;
}
Rope move_rope(Rope rope, int dx, int dy)
{
rope.head.first += dx;
rope.head.second += dy;
if (rope.head.first == rope.tail.first)
{ //same x
if (rope.head.second > rope.tail.second)
{
rope.tail.second = rope.head.second-1;
}
else if (rope.head.second < rope.tail.second)
{
rope.tail.second = rope.head.second+1;
}
}
else if (rope.head.second == rope.tail.second)
{ //same y
if (rope.head.first > rope.tail.first)
{
rope.tail.first = rope.head.first-1;
}
else if (rope.head.first < rope.tail.first)
{
rope.tail.first = rope.head.first+1;
}
}
else
{ //diagonal
if (abs(rope.head.first-rope.tail.first) == 1 && abs(rope.head.second-rope.tail.second) == 1)
{
return rope;
}
if (rope.head.first-rope.tail.first > 0)
{
rope.tail.first++;
}
else
{
rope.tail.first--;
}
if (rope.head.second-rope.tail.second > 0)
{
rope.tail.second++;
}
else
{
rope.tail.second--;
}
}
return rope;
}