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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if 0
#define KNOTS 2
#else
#define KNOTS 10
#endif
#if 0
#define FILENAME "sample.txt"
#else
#define FILENAME "input.txt"
#endif
#define SIDE 1000
#define OFFSET (SIDE/2)
typedef enum {
NONE = 0,
NORTH = 1,
SOUTH = -1,
EAST = 1,
WEST = -1
} direction;
int board[SIDE][SIDE] = {0};
int rope[KNOTS][2] = {0};
direction rope_dir[KNOTS][2] = {0};
void move(int k)
{
rope[k][0] += rope_dir[k][0];
rope[k][1] += rope_dir[k][1];
}
void parse_dir(char d)
{
rope_dir[0][0] = NONE;
rope_dir[0][1] = NONE;
switch(d) {
case 'U':
rope_dir[0][1] = NORTH;
return;
case 'D':
rope_dir[0][1] = SOUTH;
return;
case 'R':
rope_dir[0][0] = EAST;
return;
case 'L':
rope_dir[0][0] = WEST;
return;
}
}
void parse()
{
FILE *fp = fopen(FILENAME, "r");
if(!fp) {
fprintf(stderr, "ERROR: Could not open file: %s\n", FILENAME);
exit(1);
}
char line[256];
while(fgets(line, sizeof(line), fp))
{
parse_dir(strtok(line, " ")[0]);
int n = atoi(strtok(NULL, " "));
for(int i = 0; i < n; i++)
{
move(0);
for(int j = 1; j < KNOTS; j++)
{
int hor = rope[j-1][0] - rope[j][0];
if(hor > 0) rope_dir[j][0] = EAST;
else if(hor < 0) rope_dir[j][0] = WEST;
else rope_dir[j][0] = NONE;
int vert = rope[j-1][1] - rope[j][1];
if(vert > 0) rope_dir[j][1] = NORTH;
else if(vert < 0) rope_dir[j][1] = SOUTH;
else rope_dir[j][1] = NONE;
if(abs(vert) > 1 || abs(hor) > 1)
move(j);
}
board[rope[KNOTS-1][0] + OFFSET][rope[KNOTS-1][1] + OFFSET]++;
}
}
fclose(fp);
}
int sum()
{
int sum = 0;
for(int i = 0; i < SIDE; i++)
for(int j = 0; j < SIDE; j++)
if(board[j][i] > 0) sum++;
return sum;
}
int main(void)
{
parse();
printf("%d\n", sum());
return 0;
}
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