34 lines
920 B
C
34 lines
920 B
C
#include <stdio.h>
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#define put(x, y) intersections += ++map[x][y] == 2
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int main(void) {
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FILE *fp = fopen("input.txt", "r");
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unsigned char map[1000][1000] = {0};
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unsigned x0, x1, y0, y1;
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unsigned intersections = 0;
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while (fscanf(fp, "%u,%u -> %u,%u", &x0, &y0, &x1, &y1) == 4) {
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char incY = y0 < y1 ? 1 : -1;
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char incX = x0 < x1 ? 1 : -1;
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if (x0 == x1) {
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for (unsigned y = y0; y != y1; y += incY)
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put(x0, y);
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put(x0, y1);
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} else if (y0 == y1) {
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for (unsigned x = x0; x != x1; x += incX)
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put(x, y0);
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put(x1, y0);
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} else {
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unsigned x = x0, y = y0;
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while (x != x1 && y != y1) {
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put(x, y);
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x += incX;
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y += incY;
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}
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put(x, y);
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}
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}
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printf("Answer: %d\n", intersections);
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}
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