A. Alex and a Rhombus

题目链接：http://codeforces.com/contest/1180/problem/A

题目：

While playing with geometric figures Alex has accidentally invented a concept of an-th order rhombusin a cell grid.A1-st order rhombusis just a square1×1(i.e just a cell).An-th order rhombusfor alln≥2one obtains from an−1-th order rhombusadding 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.
InputThe first and only input line contains integern(1≤n≤100) — order of a rhombus whose numbers of cells should be computed.
OutputPrint 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
NoteImages of rhombus corresponding to the examples are given in the statement.

题意：求第N个图形的小方格个数

思路：

找规律题：

1+3+5+7+..+5+3+1

#include<bits/stdc++.h>

typedef long long ll;

using namespace std;

const int maxn=2e5+;

ll ji[maxn];

int main()

{

        int n;

        while(cin>>n) {

            ll ji[maxn];

            ji[]=;

            for(int i=;i<;i++)

            {

                ji[i]=ji[i-]+;

            }

            if (n == )

                cout <<  << endl;

            else if (n == )

                cout <<  << endl;

            else {

                ll sum = ;

                for (int i = ; i <= n - ; i++)

                {

                    sum += ji[i];

                }

                cout <<  * sum + ji[n - ] << endl;

            }

        }

    return ;

}

巴特西

Codeforces Round #569 (Div. 2)A. Alex and a Rhombus

A. Alex and a Rhombus

题目：

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