103 lines
2.4 KiB
C
103 lines
2.4 KiB
C
#include <math.h>
|
|
#include <stdio.h>
|
|
|
|
#define ABS(x) (((x) < 0) ? -(x) : (x))
|
|
#define SQR(x) ((x) * (x))
|
|
#define DET(a, b, c, d) ((a) * (d) - (b) * (c))
|
|
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
|
|
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
|
|
|
|
typedef struct {
|
|
long x, y;
|
|
} poin_t;
|
|
|
|
typedef struct {
|
|
float x, y;
|
|
} fpoin_t;
|
|
|
|
long area2(poin_t A, poin_t B, poin_t C)
|
|
{
|
|
return ABS(DET(C.x - A.x, A.x - B.x, C.y - A.y, A.y - B.y));
|
|
}
|
|
|
|
int main()
|
|
{
|
|
FILE *f = fopen("DG.INP", "r");
|
|
char n, i, c = 0, b;
|
|
poin_t M, N, P, Q, polygon[101];
|
|
fpoin_t tmp, intersections[2];
|
|
long Mout = 0, Nout, d;
|
|
double res;
|
|
|
|
fscanf(f, "%hhd", &n);
|
|
for (i = 0; i < n; i++)
|
|
fscanf(f, "%ld %ld", &polygon[i].x, &polygon[i].y);
|
|
fscanf(f, "%ld %ld %ld %ld", &M.x, &M.y, &N.x, &N.y);
|
|
fclose(f);
|
|
f = fopen("DG.OUT", "w");
|
|
if (M.x == N.x && M.y == N.y) {
|
|
fputs("0\n", f);
|
|
fclose(f);
|
|
return 0;
|
|
}
|
|
|
|
for (i = 1; i < n - 1; i++)
|
|
Mout += area2(*polygon, polygon[i], polygon[i + 1]);
|
|
for (Nout = Mout, polygon[n] = *polygon, i = 0; i < n; i++) {
|
|
Mout -= area2(M, polygon[i], polygon[i + 1]);
|
|
Nout -= area2(N, polygon[i], polygon[i + 1]);
|
|
}
|
|
if (!Mout && !Nout) {
|
|
fprintf(f, "%ld\n",
|
|
(long) (sqrt(SQR(M.x - N.x) + SQR(M.y - N.y)) * 100));
|
|
fclose(f);
|
|
return 0;
|
|
}
|
|
|
|
for (i = 0; i < n; i++) {
|
|
P = polygon[i];
|
|
Q = polygon[i + 1];
|
|
d = DET(M.x - N.x, M.y - N.y, P.x - Q.x, P.y - Q.y);
|
|
if (!d)
|
|
continue;
|
|
|
|
tmp.x = DET(DET(M.x, M.y, N.x, N.y), M.x - N.x,
|
|
DET(P.x, P.y, Q.x, Q.y), P.x - Q.x) / (double) d;
|
|
tmp.y = DET(DET(M.x, M.y, N.x, N.y), M.y - N.y,
|
|
DET(P.x, P.y, Q.x, Q.y), P.y - Q.y) / (double) d;
|
|
|
|
if (tmp.x < MAX(MIN(M.x, N.x), MIN(P.x, Q.x))
|
|
|| tmp.x > MIN(MAX(M.x, N.x), MAX(P.x, Q.x))
|
|
|| tmp.y < MAX(MIN(M.y, N.y), MIN(P.y, Q.y))
|
|
|| tmp.y > MIN(MAX(M.y, N.y), MAX(P.y, Q.y)))
|
|
continue;
|
|
|
|
for (b = d = 0; d < c; d++)
|
|
if (intersections[d].x == tmp.x
|
|
&& intersections[d].y == tmp.y)
|
|
b = 1;
|
|
if (b)
|
|
continue;
|
|
|
|
intersections[c].x = tmp.x;
|
|
intersections[c].y = tmp.y;
|
|
c++;
|
|
}
|
|
|
|
if (!Mout && c)
|
|
res = SQR(M.x - intersections[0].x)
|
|
+ SQR(M.y - intersections[0].y);
|
|
else if (!Nout && c)
|
|
res = SQR(N.x - intersections[0].x)
|
|
+ SQR(N.y - intersections[0].y);
|
|
else if (c == 2)
|
|
res = SQR(intersections[0].x - intersections[1].x)
|
|
+ SQR(intersections[0].y - intersections[1].y);
|
|
else
|
|
res = 0;
|
|
fprintf(f, "%ld\n", (long) (sqrt(res) * 100));
|
|
fclose(f);
|
|
|
|
return 0;
|
|
}
|