wordcraft（陈高远）

#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <cctype>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#ifdef WIN32
#define fmt64 "%I64d"
#else
#define fmt64 "%lld"
#endif
#define PI M_PI
#define oo 0x13131313
#define iter iterator
#define fst first
#define snd second
#define PB push_back
#define MP make_pair
#define FOR(i, j, k) for (i = (j); i <= (k); ++i)
#define ROF(i, j, k) for (i = (j); i >= (k); --i)
#define FER(i, j, k) for (edge *i = j[k]; i; i = i->n)
#define FRE(i, a) for (i = a.begin(); i != a.end(); ++i)
using namespace std;
template<class T> inline bool minim(T &a, const T &b) {return b < a ? a = b, 1 : 0;}
template<class T> inline bool maxim(T &a, const T &b) {return b > a ? a = b, 1 : 0;}
template<class T> inline T sqr(const T &a) {return a * a;}
typedef unsigned int uint;
typedef long long int64;
typedef unsigned long long uint64;
typedef long double real;
#define maxn 100002
struct edge{int t; edge *n;}es[maxn], *adj = es, *lst[maxn];
void link(int i, int j)
{
    *(++adj) = (edge){j, lst[i]}, lst[i] = adj;
}
int sg[maxn], sgs[maxn]; bool ok[maxn];
struct function_get_sg
{
    int flag, f[maxn]; bool root;
    void dfs(int u, int sum)
    {
        if (u) {
            f[sum ^ sgs[u]] = flag;
            if (root && !(sum ^ sgs[u]))
                ok[u] = 1;
        }
        FER(e, lst, u) dfs(e->t, sum ^ sgs[u] ^ sg[e->t]);
    }
    void operator()(int u)
    {
        root = !u;
        FER(e, lst, u) sgs[u] ^= sg[e->t];
        ++flag, dfs(u, 0);
        for (int i = 0; ; ++i) if (f[i] != flag) {sg[u] = i; return;}
    }
} get_sg;
void dfs(int u)
{
    FER(e, lst, u)
        dfs(e->t);
    get_sg(u);
}
int n, maxLen; char st[maxn][105], *tt;
inline bool prefix(char *s, char *t)
{
    for (; *t; ++s, ++t) if (!*s || *s != *t) break;
    return !*s;
}
void input()
{
    int i, j; static int fa[maxn];
    scanf("%d%d\n", &n, &maxLen);
    FOR(i, 1, n) {
        char *c = st[i], *s = c;
        for (; ~(*c = getchar()) && *c != '\n'; ++c);
        *c = 0;
        for (j = i - 1; j && !prefix(st[j], s); j = fa[j]);
        link(j, i), fa[i] = j;
    }
}
void print()
{
    int i, j = 0;
    FOR(i, 1, n) if (ok[i]) {
        char *s = st[i];
        for (; *s; ++s)
            if (putchar(*s), ++j == 50) putchar('\n'), j = 0;
    }
}
int main()
{
    input();
    dfs(0);
    if (!sg[0]) puts("Can’t win at all!!"), exit(0);
    print();
}