BZOJ 1875: [SDOI2009]HH去散步

刷水严重啊。

 

// {HEAD
#define FILE_IN_OUT
#define debug
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <algorithm>
#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <complex>
#include <string>
#define REP(i, j) for (int i = 0; i < j; ++i)
#define REPI(i, j, k) for (int i = j; i <= k; ++i)
#define REPD(i, j) for (int i = j; 0 < i; --i)
#define STLR(i, con) for (int i = 0, sz = con.size(); i < sz; ++i)
#define STLRD(i, con) for (int i = con.size() - 1; 0 <= i; --i)
#define CLR(s) memset(s, 0, sizeof s)
#define SET(s, v) memset(s, v, sizeof s)
#define pb push_back
#define PL(k, n) for (int i = 1; i <= n; ++i) { cout << k[i] << ' '; } cout << endl
#define PS(k) STLR(i, k) { cout << k[i] << ' '; } cout << endl
using namespace std;
#ifdef debug
#ifndef ONLINE_JUDGE
    const int OUT_PUT_DEBUG_INFO = 1;
#endif
#endif
#ifdef ONLINE_JUDGE
    const int OUT_PUT_DEBUG_INFO = 0;
#endif
#define DG if(OUT_PUT_DEBUG_INFO)
void FILE_INIT(string FILE_NAME) {
#ifdef FILE_IN_OUT
#ifndef ONLINE_JUDGE 
    freopen((FILE_NAME + ".in").c_str(), "r", stdin);
    freopen((FILE_NAME + ".out").c_str(), "w", stdout);
 
#endif
#endif
}
typedef long long LL;
typedef double DB;
typedef pair<int, int> i_pair;
const int INF = 0x3f3f3f3f;
//}
 
 
const int maxn = 121;
int n, m, t, start, end;
 
int mod = 45989;
struct Matrix {
    int d[maxn][maxn];
    int row, col;
    Matrix() {
        memset(d, 0, sizeof d);
    }
    Matrix operator * (const Matrix &rhs) {
        Matrix ret;
        ret.row = row;
        ret.col = rhs.col;
        for(int i = 1; i <= row; ++i) {
            for(int j = 1; j <= rhs.col; ++j) {
                for(int k = 1; k <= col; ++k) {
                    (ret.d[i][j] += d[i][k] * rhs.d[k][j]) %= mod;
                }
            }
        }
        return ret;
    }
    void print() {
        for(int i = 1; i <= row; ++i) {
            for(int j = 1; j < col; ++j) {
                printf("%d ", d[i][j]);
            }
            printf("%d
", d[i][col]);
        }
    }
};
 
Matrix fast_pow(Matrix base, int index) {
    Matrix ret;
    ret.col = ret.row = base.col;
    for(int i = 1; i <= ret.col; ++i) {
        ret.d[i][i] = 1;
    }
    for(; index; index >>= 1, base = base * base) {
        if(index & 1) {
            ret = ret * base;
        }
    }
    return ret;
}
 
int E[maxn][3], cnt;
 
int main() {
    FILE_INIT("BZOJ1875");
 
    cin >> n >> m >> t >> start >> end;
    ++start, ++end;
    REP(i, m) {
        int a, b;
        cin >> a >> b;
        ++a, ++b;
        E[++cnt][0] = a;
        E[cnt][1] = b;
        E[cnt][2] = i;
        E[++cnt][0] = b;
        E[cnt][1] = a;
        E[cnt][2] = i;
    }
    Matrix M;
    M.col = M.row = m * 2;
    for(int i = 1; i <= cnt; ++i) {
        for(int j = 1; j <= cnt; ++j) {
            if(E[i][0] == E[j][1] && E[i][2] != E[j][2]) {
                M.d[j][i] = 1;
            }
        }
    }
    M = fast_pow(M, t - 1);
    int ans = 0;
    for(int i = 1; i <= cnt; ++i) {
        for(int j = 1; j <= cnt; ++j) {
            if(E[i][0] == start && E[j][1] == end) {
                ans = (ans + M.d[i][j]) % mod;
            }
        }
    }
    printf("%d
", ans);
     
    return 0;
}