[POI2010]CHO-Hamsters

KMP暴力求出next数组后
实际上是一个最短路问题，floyed搞一搞
然而会TLE
矩阵优化一下即可（倍增floyed）
KMP在弱数据下可以AC。。正解请看其他人博客

# include 
# include 
# include 
# include 
# include 
# define IL inline
# define RG register
# define Fill(a, b) memset(a, b, sizeof(a))
using namespace std;
typedef long long ll;

IL ll Read(){
    RG char c = getchar(); RG ll x = 0, z = 1;
    for(; c < '0' || c > '9'; c = getchar()) z = c == '-' ? -1 : 1;
    for(; c >= '0' && c <= '9'; c = getchar()) x = (x << 1) + (x << 3) + c - '0';
    return x * z;
}

int n, m, nxt[210][100010], len[210];
char s[210][100010];
struct Matrix{
    ll a[210][210];
    IL void Clear(){  Fill(a, 63);  }
    IL ll* operator [](RG int x){  return a[x];  }
    IL Matrix operator *(RG Matrix &B){
        RG Matrix C; C.Clear();
        for(RG int i = 0; i <= n; i++)
            for(RG int j = 0; j <= n; j++)
                for(RG int k = 0; k <= n; k++)
                    C[i][k] = min(C[i][k], a[i][j] + B[j][k]);
        return C;
    }
} ans, edge;

int main(RG int argc, RG char* argv[]){
    edge.Clear(); ans.Clear();
    n = Read(); m = Read();
    for(RG int i = 1; i <= n; i++)
        scanf(" %s", s[i] + 1), len[i] = strlen(s[i] + 1);
    for(RG int k = 1; k <= n; k++)
        for(RG int i = 2, j = 0; i <= len[k]; i++){
            while(j && s[k][j + 1] != s[k][i]) j = nxt[k][j];
            if(s[k][j + 1] == s[k][i]) j++;
            nxt[k][i] = j;
        }
    for(RG int x = 1; x <= n; x++){
        edge[0][x] = len[x];
        for(RG int y = 1; y <= n; y++)
            for(RG int i = 2, j = 0; i <= len[x]; i++){
                while(j && s[y][j + 1] != s[x][i]) j = nxt[y][j];
                if(s[y][j + 1] == s[x][i]) j++;
                if(i == len[x]) edge[x][y] = len[y] - j;
            }
    }
    for(RG int i = 0; i <= n; i++) ans[i][i] = 0;
    for(; m; m >>= 1, edge = edge * edge) if(m & 1) ans = ans * edge;
    RG ll min_len = 1e18;
    for(RG int i = 1; i <= n; i++) min_len = min(ans[0][i], min_len);
    printf("%lld\n", min_len);
    return 0;
}

转载于:https://www.cnblogs.com/cjoieryl/p/8206388.html