Ural-1966-cycling Roads (and check collection + Sentencing line intersection)

Serie A champions: N Integrals, M Edge (1≤m < n≤200), Q: Whether all point connections (two edges intersect. The 4-point connection).

Topics Link: http://acm.timus.ru/problem.aspx?space=1&num=1966

-->> for each edge, the end points on the edge are incorporated into the collection, enumerating edges and edges. Infer whether they intersect, the points are merged into the collection, and the number of elements within the set is N.

#include <cstdio> #include <cmath>const int maxn = + 10;const Double EPS = 1e-8;struct point{double x;    Double y; Point () {} point (double x, double y): X (x), Y (y) {}} p[maxn];int N, M;int Fa[maxn], Cnt[maxn];int U[MAXN], v[maxn];typed EF point Vector; Vector operator-(vector A, vector B) {return vector (a.x-b.x, a.y-b.y);}    int dcmp (double x) {if (Fabs (x) < EPS) return 0; return x > 0? 1:-1;} Double Dot (vector A, vector B) {return a.x * b.x + a.y * B.Y;} Double Cross (vector A, vector B) {return a.x * b.y-a.y * b.x;}    BOOL Segmentproperintersection (Point-A1, Point-A2, point-B1, point-B2) {Double C1 = Cross (A2-A1, B1-A1);    Double C2 = Cross (A2-A1, B2-A1);    Double C3 = Cross (B2-B1, A1-B1);    Double C4 = Cross (b2-b1, A2-B1); Return DCMP (C1) * DCMP (C2) < 0 && dcmp (C3) * DCMP (C4) < 0;} BOOL Onsegment (point P, point A1, point A2) {return dcmp (cross (a1-p, a2-p)) = = 0 && dcmp (Dot (a1-p, A2- p)) < 0;}        void Init () {for (int i = 1; I <= n; ++i) {fa[i] = i;    Cnt[i] = 1; }}int find (int x) {return x = = Fa[x]? x: (Fa[x] = find (fa[x]));}    void Union (int x, int y) {int xroot = Find (x);    int yroot = Find (y);        if (xroot! = yroot) {Fa[yroot] = Xroot;    Cnt[xroot] + = Cnt[yroot];    }}void Read () {for (int i = 1; I <= n; ++i) {scanf ("%lf%lf", &p[i].x, &AMP;P[I].Y);        } for (int i = 0; i < m; ++i) {scanf ("%d%d", U + I, v + i);        Union (U[i], v[i]);  for (int j = 1; j <= N; ++j) {if (J! = U[i] && J! = V[i] && onsegment (P[j], P[u[i]],            P[v[i]]) {Union (J, U[i]);            }}}}void Merge () {for (int i = 0; i < m; ++i) {for (int j = i + 1; j < m; ++j) {            if (Segmentproperintersection (P[u[i]], P[v[i]], P[u[j]], P[v[j]])) {Union (U[i], u[j]); }}}}void Output () {cnt[find (1)] = = n? 
Puts ("YES"): Puts ("NO");}        int main () {while (scanf ("%d%d", &n, &m) = = 2) {Init ();        Read ();        Merge ();    Output (); } return 0;}

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Ural-1966-cycling Roads (and check collection + Sentencing line intersection)