- Codeforces Round #569 (Div. 2) https://codeforces.com/contest/1180
- A. Alex and a Rhombus https://codeforces.com/contest/1180/problem/A
- While playing with geometric figures Alex has accidentally invented a concept of a n-th order rhombus in a cell grid.
- A1-st order rhombus is just a square 1*1 (i.e just a cell).
An-th order rhombus for all n≥2 one obtains from a n−1-th order rhombus adding all cells which have a common side with it to it (look at the picture to understand it better).
- Alex asks you to compute the number of cells in a n-th order rhombus.
- Input
- The first and only input line contains integer n (1≤n≤100) - order of a rhombus whose numbers of cells should be computed.
- Output
- Print exactly one integer - the number of cells in a n-th order rhombus.
- Examples
- input
- 1
- output
- 1
- input
- 2
- output
- 5
- input
- 3
- output
- 13
- Note
Images of rhombus corresponding to the examples are given in the statement.
思路: 感觉是找规律题, 推一下找找规律就好了......
- #include<iostream>
- #include<cstring>
- #include<cstdio>
- #include<cmath>
- #include<algorithm>
- #include<map>
- #include<set>
- #include<vector>
- #include<queue>
- using namespace std;
- #define ll long long
- const int mod=1e9+7;
- const int inf=1e9+7;
- //const int maxn=
- int main()
- {
- iOS::sync_with_stdio(false);cin.tie(0);cout.tie(0);
- int n;
- while(cin>>n)
- {
- int ans=0;
- int f=(n<<1)-1;
- ans+=f;
- f-=2;
- while(f!=-1)
- {
- ans+=(f<<1);
- f-=2;
- }
- cout<<ans<<endl;
- }
- return 0;
- }
来源: http://www.bubuko.com/infodetail-3100734.html