/* * POJ3090 Visible Lattice Points * 欧拉函数 */ #include<cstdio> using namespace std; int C,N; //欧拉函数模板 int Euler(int n) { int num = n; for(int i = 2;i <= n;i++) { if(n % i == 0) { num = num / i * (i-1); } while(n % i == 0) { n /= i; } } return num…

Description A lattice point (x, y) in the first quadrant (x and y are integers greater than or equal to 0), other than the origin, is visible from the origin if the line from (0, 0) to (x, y) does not pass through any other lattice point. For example…

欧拉函数裸题,直接欧拉函数值乘二加一就行了.具体证明略,反正很简单. 题干: Description A lattice point (x, y) in the first quadrant (x and y are integers greater than or equal to 0), other than the origin, is visible from the origin if the line from (0, 0) to (x, y) does not pass throu…

题目链接:传送门 思路: 所有gcd(x, y) = 1的数对都满足题意,然后还有(1, 0) 和 (0, 1). #include <iostream> #include <cstring> using namespace std; ; ], phi[MAX_N+]; void getPrime_and_Phi() { memset(prime, , sizeof prime); phi[] = ; ; i <= MAX_N; i++) { ]] = i, phi[i] =…

答案为3+2*∑φ(i),(i=2 to n) Code #include <cstdio> int T,n,A[1010]; void Init(){ for(int i=2;i<=1000;++i)A[i]=i; for(int i=2;i<=1000;++i) if(A[i]==i)for(int j=i;j<=1000;j+=i) A[j]=A[j]/i*(i-1); for(int i=3;i<=1000;++i)A[i]+=A[i-1]; } int mai…

题目大意:给出范围为(0, 0)到(n, n)的整点,你站在原点处,问有多少个整点可见. 线y=x和坐标轴上的点都被(1,0)(0,1)(1,1)挡住了.除这三个钉子外,如果一个点(x,y)不互质,则它就会被点(x0, y0) (x0,y0互质,x/x0==y/y0)挡住.能看见的钉子关于线y=x对称.所以,求出x=2至n的所有与x互质的数的个数φ(x)的和(也就是线y=x右下角(因为φ(x)<x)所有能看见的点的个数)乘以2(对角线两旁的看见的点的个数)+3(那几个特殊点)即为所求. 求φ值时…

Visible Lattice Points Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 5636   Accepted: 3317 Description A lattice point (x, y) in the first quadrant (x and y are integers greater than or equal to 0), other than the origin, is visible fr…

SPOJ Problem Set (classical) 7001. Visible Lattice Points Problem code: VLATTICE Consider a N*N*N lattice. One corner is at (0,0,0) and the opposite one is at (N,N,N). How many lattice points are visible from corner at (0,0,0) ? A point X is visible…

http://poj.org/problem?id=3090 Visible Lattice Points Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 6153   Accepted: 3662 Description A lattice point (x, y) in the first quadrant (x and y are integers greater than or equal to 0), other…

题目:http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=37193   Visible Lattice Points Time Limit: 1368MS   Memory Limit: 1572864KB   64bit IO Format: %lld & %llu Submit Status Description Consider a N*N*N lattice. One corner is at (0,0,0) and…