Coloring Game（思维题）

标签：lin   输入   tput   orm   def   cst   algo   VID   .com   

David has a white board with 2×N2 \times N2×N grids.He decides to paint some grids black with his brush.He always starts at the top left corner and ends at the bottom right corner, where grids should be black ultimately.

Each time he can move his brush up(↑), down(↓), left(←), right(→), left up(↖), left down(↙), right up(↗), right down (↘) to the next grid.

For a grid visited before,the color is still black. Otherwise it changes from white to black.

David wants you to compute the number of different color schemes for a given board. Two color schemes are considered different if and only if the color of at least one corresponding position is different.

Input

One line including an integer n(0<n≤109)n(0<n \le 10^9)n(0<n≤109)

Output

One line including an integer, which represent the answer ?mod?1000000007\bmod 1000000007mod1000000007

2

4

3

12

#include <cstdio>
#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
#define ll long long
const int inf = 0x3f3f3f3f;
const  ll linf  =1LL<<50;
const int maxn = 1e5+8;
const ll mod = 1000000007;
ll qsm(ll a, ll b)
{
  ll sum = 1;
  a = a%mod;
  while(b)
  {
      if(b&1)
      {
          sum = (sum*a)%mod;
      }
      b /= 2;
      a = (a*a)%mod;
  }
  return sum;
}
int main()
{
    ll n;
    scanf("%lld", &n);
    ll sum = 4*qsm(3, n-2);
    printf("%lld\n", sum);
    return 0;
}

Coloring Game（思维题）

标签：lin   输入   tput   orm   def   cst   algo   VID   .com   

原文地址：https://www.cnblogs.com/RootVount/p/10752643.html