UVA 1595-symmetry

Idea: First, if these points are symmetrical, then their symmetric axes are x = m (M is the average of all points);

Place these points in a set and then scan each point to calculate its symmetry point for x = m to see if the point is in the set.

If one is not present, the description cannot form a symmetric graphic.

1#include <iostream>2#include <algorithm>3#include <cstdio>4#include <Set>5 using namespacestd;6 7 structpoint{8     intx, y;9Point (intx =0,inty =0): X (x), Y (y) {}Ten     BOOL operator< (ConstPoint & RHS)Const One     { A         returnX < Rhs.x | | (x = = Rhs.x && y <rhs.y); -     } - }; the  - Const intMAXN = ++Ten; - Point P[MAXN]; -  + intMain () - { +     intT, N; A     Set<Point>SP; atscanf"%d", &T); -      while(t--) -     { -         Doubles =0, M; - sp.clear (); -scanf"%d", &n); in          for(inti =0; I < n; i++) -         { toCIN >> p[i].x >>p[i].y; + Sp.insert (P[i]); -s + =p[i].x; the         } *m = S/n;//m:must to is a integer. $         BOOLOK =true;Panax Notoginseng          for(inti =0; I < n; i++) -         { thePoint T ((int) (m*2)-p[i].x, p[i].y); +             if(!Sp.count (t)) A             { theOK =false; +                  Break; -             } $         } $printf"%s\n"Ok?"YES":"NO"); -     } -     return 0; the}

UVA 1595-symmetry