hdu 5955 Guessing the Dice Roll

（AC自动机+高斯消元）

注：期望逆着推，概率顺着推

#include"queue"
#include"cmath"
#include"cstdio"
#include"cstring"
#include"iostream"
#include"algorithm"
using namespace std;
const int MX = 121;
int a[21][21];
char s[21];
typedef double Matrix[MX][MX];
Matrix A;
void gauss(Matrix A, int n) {
    int i, j, k, r;
    for(i = 0; i < n; i++) {
        r = i;
        for(int j = i + 1; j < n; j++) {
            if(fabs(A[j][i]) > fabs(A[r][i])) r = j;
        }
        if(r != i) for(j = 0; j <= n; j++) swap(A[r][j], A[i][j]);
        for(int k = i+1; k <= n; k++)   A[i][k] /= A[i][i];
        A[i][i] = 1;

        for(k = i+1; k < n; k++)
        if(k!=i){
            double f = A[k][i] / A[i][i];
            for(j = i; j <= n; j++) A[k][j] -= f * A[i][j];
        }
    }

    for(int i = n-1; i >=0; i--){
        for(int j = i-1; j >= 0; j--){
            double f = A[j][i]/A[i][i];
            A[j][i] -= f*A[i][i];
            A[j][n] -= f*A[i][n];
        }
    }
}

struct AC_machine {
    int rear, root;
    int Next[MX][6], Fail[MX], End[MX], id[11];
    void Init() {
        rear = 0;
        root = New();
    }
    int New() {
        End[rear] = 0;
        for(int i = 0; i < 6; i++) {
            Next[rear][i] = -1;
        }
        return rear++;
    }
    void Add(char *A, int I) {
        int n = strlen(A), now = root;
        for(int i = 0; i < n; i++) {
            int id = A[i] - '1';
            if(Next[now][id] == -1) {
                Next[now][id] = New();
            }
            now = Next[now][id];
        }
        End[now] = 1;
        id[I] = now;
    }
    void Build() {
        queue<int> Q;
        Fail[root] = root;
        for(int i = 0; i < 6; i++) {
            if(Next[root][i] == -1) {
                Next[root][i] = root;
            } else {
                Fail[Next[root][i]] = root;
                Q.push(Next[root][i]);
            }
        }
        while(!Q.empty()) {
            int u = Q.front(); Q.pop();
            if(End[Fail[u]]) End[u] = 1;
            for(int i = 0; i < 6; i++) {
                if(Next[u][i] == -1) {
                    Next[u][i] = Next[Fail[u]][i];
                } else {
                    Fail[Next[u][i]] = Next[Fail[u]][i];
                    Q.push(Next[u][i]);
                }
            }
        }
    }
    void matrix(Matrix A) {
        for(int i = 0; i <= rear; i++)
           for(int j = 0; j <= rear; j++)
                A[i][j] = 0;

        for(int i = 0; i < rear; i++){
            if(!End[i]){
                for(int j =0 ; j < 6; j++){
                    int v = Next[i][j];
                    A[v][i] += 1.0/6.0;
                }
            }
            A[i][i] += -1;
        }
        A[0][rear] = -1;
    }
    void out()
    {
        for(int i = 0; i < rear; i++){
            for(int j = 0; j <= rear; j++)
                printf("%.6lf ",A[i][j]);
            printf("\n");
        }
        printf("\n\n");
    }
    void print(int n)
    {
        for(int i = 1; i <= n; i++){
            if(i > 1) printf(" ");
            printf("%.6lf",A[id[i]][rear]);
        }
        printf("\n");
    }
} AC;


int main()
{
    int T,n,m;
    scanf("%d",&T);
    while(T--){
        AC.Init();
        scanf("%d%d",&n,&m);
        memset(s,0,sizeof(s));
        for(int i = 1; i <= n; i++){
            for(int j = 1; j<= m; j++){
                scanf("%d",&a[i][j]);
                s[j-1] = a[i][j]+'0';
            }
            AC.Add(s,i);
        }
        AC.Build();
        AC.matrix(A);
        gauss(A,AC.rear);
        AC.print(n);
    }
    return 0;
}