Submission #3685609

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Source Code Expand

N,NX,NY,QX,QY = map(int,input().split())
src = [tuple(map(int,input().split())) for i in range(N-1)]

def cross_prod(ax,ay,bx,by,px,py):
    v1x = bx - ax
    v1y = by - ay
    v2x = px - ax
    v2y = py - ay
    return v1x * v2y - v1y * v2x

def is_crossing(x11,y11,x12,y12,x21,y21,x22,y22):
    l1_p21 = cross_prod(x11,y11,x12,y12,x21,y21)
    l1_p22 = cross_prod(x11,y11,x12,y12,x22,y22)
    l2_p11 = cross_prod(x21,y21,x22,y22,x11,y11)
    l2_p12 = cross_prod(x21,y21,x22,y22,x12,y12)
    return l1_p21 * l1_p22 < 0 and l2_p11 * l2_p12 < 0

ans = 1
for x1,y1,x2,y2 in src:
    if is_crossing(NX,NY,QX,QY,x1,y1,x2,y2):
        ans += 1
print(ans)

Submission Info

Judge Result