TOYS
Calculate the number of toys that land in each bin of a partitioned toy box.Mom and dad have a problem - their child John never puts his toys away when he is finished playing with them. They gave John a rectangular box to put his toys in, but John is rebellious and obeys his parents by simply throwing his toys into the box. All the toys get mixed up, and it is impossible for John to find his favorite toys.
John's parents came up with the following idea. They put cardboard partitions into the box. Even if John keeps throwing his toys into the box, at least toys that get thrown into different bins stay separated. The following diagram shows a top view of an example toy box.
For this problem, you are asked to determine how many toys fall into each partition as John throws them into the toy box.
Input
The input file contains one or more problems. The first line of a problem consists of six integers, n m x1 y1 x2 y2. The number of cardboard partitions is n (0 < n <= 5000) and the number of toys is m (0 < m <= 5000). The coordinates of the upper-left corner and the lower-right corner of the box are (x1,y1) and (x2,y2), respectively. The following n lines contain two integers per line, Ui Li, indicating that the ends of the i-th cardboard partition is at the coordinates (Ui,y1) and (Li,y2). You may assume that the cardboard partitions do not intersect each other and that they are specified in sorted order from left to right. The next m lines contain two integers per line, Xj Yj specifying where the j-th toy has landed in the box. The order of the toy locations is random. You may assume that no toy will land exactly on a cardboard partition or outside the boundary of the box. The input is terminated by a line consisting of a single 0.
Output
The output for each problem will be one line for each separate bin in the toy box. For each bin, print its bin number, followed by a colon and one space, followed by the number of toys thrown into that bin. Bins are numbered from 0 (the leftmost bin) to n (the rightmost bin). Separate the output of different problems by a single blank line.
Sample Input
5 6 0 10 60 0
3 1
4 3
6 8
10 10
15 30
1 5
2 1
2 8
5 5
40 10
7 9
4 10 0 10 100 0
20 20
40 40
60 60
80 80
5 10
15 10
25 10
35 10
45 10
55 10
65 10
75 10
85 10
95 10
0
Sample Output
0: 2
1: 1
2: 1
3: 1
4: 0
5: 1
0: 2
1: 2
2: 2
3: 2
4: 2
Hint
As the example illustrates, toys that fall on the boundary of the box are "in" the box.
Source
题目类型：叉乘+二分枚举
算法分析：使用叉乘可以判断点在一个线段的左侧还是右侧。然后二分枚举直线并判断即可
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/************************************************* Author :supermaker Created Time :2016/1/24 10:51:12 File Location :C:\Users\abcd\Desktop\TheEternalPoet **************************************************/ #pragma comment(linker, "/STACK:102400000,102400000") #include <set> #include <bitset> #include <list> #include <map> #include <stack> #include <queue> #include <deque> #include <string> #include <vector> #include <ios> #include <iostream> #include <fstream> #include <sstream> #include <iomanip> #include <algorithm> #include <utility> #include <complex> #include <numeric> #include <functional> #include <cmath> #include <ctime> #include <climits> #include <cstdarg> #include <cstdio> #include <cstdlib> #include <cstring> #include <cctype> #include <cassert> using namespace std; #define CFF freopen ("aaa.txt", "r", stdin) #define CPPFF ifstream cin ("aaa.txt") #define DB(ccc) cout << #ccc << " = " << ccc << endl #define PB push_back #define MP(A, B) make_pair(A, B) typedef long long LL; typedef unsigned long long ULL; typedef double DB; typedef pair <int, int> PII; typedef pair <int, bool> PIB; const int INF = 0x7F7F7F7F; const int MOD = 1e9 + 7; const double EPS = 1e-10; const double PI = 2 * acos (0.0); const int maxn = 5000 * 2 + 66; int n, m; int sgn (double a) { if (fabs (a) < EPS) return 0; else if (a < 0) return -1; else return 1; } struct Point { double x, y; Point () {} Point (double xx, double yy) : x (xx), y (yy) {} Point operator + (const Point &a) const { return Point (x + a.x, y + a.y); } Point operator - (const Point &a) const { return Point (x - a.x, y - a.y); } double operator ^ (const Point &a) const { return x * a.y - y * a.x; } double operator * (const Point &a) const { return x * a.x + y * a.y; } }; struct Line { Point s, e; Line () {} Line (Point ss, Point ee) : s (ss), e (ee) {} }; Line line[maxn]; int res[maxn]; double xmul (Point p1, Point p2, Point p3) { return (p2 - p1) ^ (p3 - p1); } int main() { //CFF; //CPPFF; while (scanf ("%d", &n) != EOF) { if (n == 0) break; scanf ("%d", &m); double x1, y1, x2, y2; scanf ("%lf%lf%lf%lf", &x1, &y1, &x2, &y2); for (int i = 1; i <= n; i++) { double Ui, Li; scanf ("%lf%lf", &Ui, &Li); line[i] = Line (Point (Ui, y1), Point (Li, y2)); } memset (res, 0, sizeof (res)); for (int i = 1; i <= m; i++) { double x, y; scanf ("%lf%lf", &x, &y); int low = 1, high = n; while (low <= high) { int mid = (low + high) >> 1; double tt = xmul (line[mid].s, Point (x, y), line[mid].e); if (sgn (tt) == 1) high = mid - 1; if (sgn (tt) == -1) low = mid + 1; } res[min(low,high)]++; } for (int i = 0; i <= n; i++) printf ("%d: %d\n", i, res[i]); puts (""); } return 0; } |
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