CF432D Prefixes and Suffixes

LuoGu: CF432D Prefixes and Suffixes

CF: D. Prefixes and Suffixes

求出 Z函数，合法当且仅当 $z _ i = n - i$ 。

查看代码

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long L;
const int N = 1e5 + 10;
char s[N];
int n, f[N], g[N];
void init ()
{
    for (int i = 1, t = 0; i < n; ++i)
    {
        if (t + f[t] > i) f[i] = min(f[i - t], t + f[t] - i);
        while (i + f[i] < n && s[f[i]] == s[i + f[i]]) ++f[i];
        if (i + f[i] > t + f[t]) t = i;
    }
    f[0] = n;
}
int main ()
{
    scanf("%s", s);
    n = strlen(s);
    init();
    int res = 0;
    for (int i = 0; i < n; ++i)
    {
        ++g[f[i]];
        if (f[i] == n - i) ++res;
    }
    for (int i = n - 1; i; --i) g[i] += g[i + 1];
    printf("%d\n", res);
    for (int i = n - 1; ~i; --i)
        if (f[i] == n - i) printf("%d %d\n", f[i], g[f[i]]);
    return 0;
}