hdu 4333 Revolving Digits(拓展KMP)

题目连接:hdu 4333 Revolving Digits

题目大意：给定一个数，每次将头一个数放到最后，这样形成n个数，去掉重复的后，考虑有多少个数比原先的数小，

等于，大。

解题思路：拓展KMP的应用，上模板水一下就行了。

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int maxn = 100005;

int cpfix[maxn], extand[maxn];

void getCPfix(char* str) {
    memset(cpfix, 0, sizeof(cpfix));

    int n = strlen(str + 1), tmp = 1;
    cpfix[1] = n;

    while (tmp < n && str[tmp] == str[tmp+1])
        tmp++;
    cpfix[2] = tmp-1;

    int p = 2;
    for (int k = 3; k <= n; k++) {
        // e 为目前匹配过的最末位置, l 为对应的偏移;
        int e = p + cpfix[p] - 1, l = cpfix[k-p+1];

        if (k + l - 1 >= e) {
            int j = e - k > 0 ? e - k : 0;
            while (k + j <= n && str[k+j] == str[j+1])
                j++;
            cpfix[k] = j, p = k;
        } else
            cpfix[k] = l;
    }
    /* for (int i = 1; i <= n; i++) printf("%d%c", cpfix[i], i == n ? '\n' : ' '); */
}

void getExtand(char* s, char* t) {
    getCPfix(t);

    int sn = strlen(s+1), tn = strlen(t+1);
    int n = min(sn, tn), tmp = 1;

    while (tmp <= n && s[tmp] == t[tmp])
        tmp++;
    extand[1] = tmp-1;

    int p = 1;
    for (int k = 2; k <= sn; k++) {
        int e = p + extand[p] - 1, l = cpfix[k-p+1];

        if (k + l - 1 >= e) {
            int j = e - k > 0 ? e - k : 0;
            while (k + j <= sn && j < tn && s[k+j] == t[j+1])
                j++;
            extand[k] = j, p = k;

        } else
            extand[k] = l;
    }

    /* for (int i = 1; i <= sn; i++) printf("%d%c", extand[i], i == sn ? '\n' : ' '); */
}

int fail[maxn];
int KMP (char* str) {
    int n = strlen(str+1);
    int p = fail[0] = fail[1] = 0;

    for (int i = 2; i <= n; i++) {
        while (p && str[p+1] != str[i])
            p = fail[p];

        if (str[p+1] == str[i])
            p++;
        fail[i] = p;
    }
    return n - fail[n];
}

char S[maxn * 2], T[maxn];

int main () {
    int cas;
    scanf("%d", &cas);
    for (int kcas = 1; kcas <= cas; kcas++) {
        scanf("%s", T+1);
        strcpy(S+1, T+1);
        strcat(S+1, T+1);
        int n = KMP(S);
        getExtand(S, T);

        int ans[3], tn = strlen(T+1);
        memset(ans, 0, sizeof(ans));
        for (int i = 1; i <= n; i++) {
            if (extand[i] >= tn)
                ans[1]++;
            else {
                int g = extand[i];
                if (S[1+g] < S[i+g])
                    ans[2]++;
                else
                    ans[0]++;
            }
        }
        printf("Case %d: %d %d %d\n", kcas, ans[0], ans[1], ans[2]);
    }
    return 0;
}