ZOJ 1426 Counting Rectangles
枚举两条竖线之间同时与这两条竖线相交的横线的个数cnt，这两条竖线之间能组成矩形的个数为：从cnt中任选两条横线的方案个数。
将每两条竖线之间能组成矩形的个数加起来就是结果。
1 #include <cstdio> 2 #include <cstring> 3 #include <cstdlib> 4 #include <algorithm> 5 #include <vector> 6 7 using namespace std; 8 9 const int MAXN = 110; 10 11 struct MyLine 12 { 13 int st; 14 int ed; 15 int th; 16 MyLine() {} 17 MyLine( int _st, int _ed, int _th ): st(_st), ed(_ed), th(_th) { } 18 }; 19 20 vector<MyLine> hori; 21 vector<MyLine> vert; 22 bool ok[MAXN][MAXN]; 23 24 int solved() 25 { 26 int ans = 0; 27 int lenH = hori.size(); 28 int lenV = vert.size(); 29 30 memset( ok, false, sizeof(ok) ); 31 32 for ( int i = 0; i < lenH; ++i ) 33 { 34 for ( int j = 0; j < lenV; ++j ) 35 if ( vert[j].th >= hori[i].st && vert[j].th <= hori[i].ed 36 && hori[i].th >= vert[j].st && hori[i].th <= vert[j].ed ) ok[i][j] = true; 37 } 38 39 40 for ( int i = 0; i < lenH; ++i ) 41 for ( int j = i + 1; j < lenH; ++j ) 42 { 43 int cnt = 0; 44 for ( int k = 0; k < lenV; ++k ) 45 if ( ok[i][k] && ok[j][k] ) ++cnt; 46 ans += cnt * (cnt - 1) / 2; 47 } 48 49 return ans; 50 } 51 52 int main() 53 { 54 // freopen( "input.txt", "r", stdin ); 55 int T; 56 scanf( "%d", &T ); 57 while ( T-- ) 58 { 59 int N; 60 scanf( "%d", &N ); 61 int x1, y1, x2, y2; 62 vert.clear(); 63 hori.clear(); 64 for ( int i = 0; i < N; ++i ) 65 { 66 scanf( "%d%d%d%d", &x1, &y1, &x2, &y2 ); 67 if ( x1 == x2 ) 68 { 69 if ( y1 > y2 ) swap( y1, y2 ); 70 hori.push_back( MyLine( y1, y2, x1 ) ); 71 } 72 else if ( y1 == y2 ) 73 { 74 if ( x1 > x2 ) swap( x1, x2 ); 75 vert.push_back( MyLine( x1, x2, y1 ) ); 76 } 77 } 78 79 printf( "%d\n", solved() ); 80 } 81 return 0; 82 }
