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78 lines
1.3 KiB
C++
78 lines
1.3 KiB
C++
#include <bits/stdc++.h>
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#define int long long
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#define endl "\n"
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#define IMX LONG_LONG_MAX
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#define IMN LONG_LONG_MIN
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#define debug$ if(dev)
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using namespace std;
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/* toothless. #17 */
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const int N = 1e7 + 10;
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const int M = 2e3 + 5;
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const bool dev = false;
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int n, m;
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int sum = 0;
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struct node
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{
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int mat[4][4];
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};
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node z;
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node matrix_nul(node x, node y)
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{
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memset(z.mat, 0, sizeof(z.mat));
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for(int i = 1; i <= 3; i ++ )
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{
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for(int j = 1; j <= 3; j ++ )
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{
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for(int k = 1; k <= 3; k ++ )
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{
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z.mat[i][j] += (x.mat[i][k]) % m * (y.mat[k][j]) % m;
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z.mat[i][j] %= m;
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}
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}
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}
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return z;
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}
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node matrix_pow(int k)
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{
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node t, a;
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t.mat[1][1] = 1;
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t.mat[1][2] = 1;
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t.mat[1][3] = 1;
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a.mat[1][1]=1;
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a.mat[1][2]=0;
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a.mat[1][3]=0;
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a.mat[2][1]=1;
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a.mat[2][2]=1;
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a.mat[2][3]=1;
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a.mat[3][1]=0;
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a.mat[3][2]=1;
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a.mat[3][3]=0;
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while(k)
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{
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if(k % 2 == 1) t = matrix_nul(t, a);
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k /= 2;
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a = matrix_nul(a, a);
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}
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return t;
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}
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signed main()
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{
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ios::sync_with_stdio(0);
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cin.tie(0);
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cout.tie(0);
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cin >> n >> m ;
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node temp;
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temp = matrix_pow(n - 1);
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int ans = temp.mat[1][1] * 1 + temp.mat[2][1] * 0;
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ans %= m;
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cout << ans % m ;
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return 0;
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} |