Codeforces Round #430 (Div. 2) B. Gleb And Pizza(数论)
2017-08-30 12:34
561 查看
B. Gleb And Pizza
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Gleb ordered pizza home. When the courier delivered the pizza, he was very upset, because several pieces of sausage lay on the crust, and he does not really like the crust.
The pizza is a circle of radius r and center at the origin. Pizza consists of the main part — circle of radius r - d with
center at the origin, and crust around the main part of the width d. Pieces of sausage are also circles. The radius of the i -th
piece of the sausage is ri,
and the center is given as a pair (xi, yi).
Gleb asks you to help determine the number of pieces of sausage caught on the crust. A piece of sausage got on the crust, if it completely lies on the crust.
Input
First string contains two integer numbers r and d (0 ≤ d < r ≤ 500) —
the radius of pizza and the width of crust.
Next line contains one integer number n — the number of pieces of sausage (1 ≤ n ≤ 105).
Each of next n lines contains three integer numbers xi, yi and ri ( - 500 ≤ xi, yi ≤ 500, 0 ≤ ri ≤ 500),
where xi and yi are
coordinates of the center of i-th peace of sausage, ri —
radius of i-th peace of sausage.
Output
Output the number of pieces of sausage that lay on the crust.
Examples
input
output
input
output
Note
Below is a picture explaining the first example. Circles of green color denote pieces of sausage lying on the crust.
题目大意:以原点为圆心有一个大圆,半径为r,现在给你几个圆和半径,现在问你有几个小圆完整的存在与r-d这个区间内,具体见上图
解题思路:这个题对于每个小圆来说,去check与大圆圆心的距离,然后卡一下d和r-d的长度即可,注意精度
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Gleb ordered pizza home. When the courier delivered the pizza, he was very upset, because several pieces of sausage lay on the crust, and he does not really like the crust.
The pizza is a circle of radius r and center at the origin. Pizza consists of the main part — circle of radius r - d with
center at the origin, and crust around the main part of the width d. Pieces of sausage are also circles. The radius of the i -th
piece of the sausage is ri,
and the center is given as a pair (xi, yi).
Gleb asks you to help determine the number of pieces of sausage caught on the crust. A piece of sausage got on the crust, if it completely lies on the crust.
Input
First string contains two integer numbers r and d (0 ≤ d < r ≤ 500) —
the radius of pizza and the width of crust.
Next line contains one integer number n — the number of pieces of sausage (1 ≤ n ≤ 105).
Each of next n lines contains three integer numbers xi, yi and ri ( - 500 ≤ xi, yi ≤ 500, 0 ≤ ri ≤ 500),
where xi and yi are
coordinates of the center of i-th peace of sausage, ri —
radius of i-th peace of sausage.
Output
Output the number of pieces of sausage that lay on the crust.
Examples
input
8 4 7 7 8 1 -7 3 2 0 2 1 0 -2 2 -3 -3 1 0 6 2 5 3 1
output
2
input
10 8
4
0 0 9
0 0 101 0 1
1 0 2
output
0
Note
Below is a picture explaining the first example. Circles of green color denote pieces of sausage lying on the crust.
题目大意:以原点为圆心有一个大圆,半径为r,现在给你几个圆和半径,现在问你有几个小圆完整的存在与r-d这个区间内,具体见上图
解题思路:这个题对于每个小圆来说,去check与大圆圆心的距离,然后卡一下d和r-d的长度即可,注意精度
#include <cstdio> #include <cstring> #include <iostream> #include <algorithm> #include <vector> #include <queue> #include <set> #include <map> #include <string> #include <cmath> #include <cstdlib> #include <ctime> using namespace std; typedef long long LL; int r,d,n; bool check(int x,int y,int rr) { double cnt = sqrt(x*x+y*y); if(cnt-double(rr)>=double(r-d)&&cnt+double(rr)<=r) return true; else return false; } int main() { int sum,i,x,y,rr; cin>>r>>d; cin>>n; sum=0; for(i=1;i<=n;i++) { cin>>x>>y>>rr; if(check(x,y,rr)) { sum++; } } cout<<sum<<endl; }
相关文章推荐
- 【Codeforces Round #430 (Div. 2) B】Gleb And Pizza
- Codeforces Round #430 (Div. 2) B. Gleb And Pizza
- Codeforces Round #430 (Div. 2) B. Gleb And Pizza
- Codeforces Round #430 (Div. 2) B. Gleb And Pizza
- Codeforces Round #430 B. Gleb And Pizza
- Codeforces Round #174 (Div. 2) Cows and Primitive Roots(数论)
- 【Codeforces Round #430 (Div. 2) C】Ilya And The Tree
- Codeforces Round #430 (Div. 2) D - Vitya and Strange Lesson(补题,01Trie)
- Codeforces Round #430 (Div. 2) C. Ilya And The Tree(补题)
- Codeforces Round #430 (Div. 2) C. Ilya And The Tree 树dp 统计
- Codeforces Round #430 (Div. 2) E. Nikita and game
- 【 Codeforces Round #430 (Div. 2) A 】 Kirill And The Game
- Codeforces Round #430 (Div. 2) C. Ilya And The Tree dfs+set
- Codeforces Round #430 (Div. 2) D. Vitya and Strange Lesson
- Codeforces Round #430 (Div. 2) 842C Ilya And The Tree(暴力)
- Codeforces Round #430 (Div. 2) C. Ilya And The Tree dfs+set
- Codeforces Round #304 (Div. 2) D. Soldier and Number Game 数论 筛表法
- Codeforces Round #430 (Div. 2) D. Vitya and Strange Lesson
- Codeforces Round #430 (Div. 2) C. Ilya And The Tree dfs+set
- Codeforces Round #430 (Div. 2) Vitya and Strange Lesson