【HDOJ】3518 Boring Counting

后缀数组2倍增可解。

#include <cstdio>
#include <cstring>
#include <cstdlib>

#define MAXN 1005
#define INF 0xfffff
#define MAXM 27

int wa[MAXN], wb[MAXN], ws[MAXN], wv[MAXN];
char s[MAXN];
int str[MAXN], sa[MAXN];
int height[MAXN], rank[MAXN];

int max(int a, int b) {
    return a>b ? a:b;
}

int min(int a, int b) {
    return a<b ? a:b;
}

int cmp(int *r, int a, int b, int l) {
    return r[a]==r[b] && r[a+l]==r[b+l];
}

void da(int *r, int *sa, int n, int m) {
    int i, j, *x = wa, *y = wb, *t;
    int p;

    for (i=0; i<m; ++i) ws[i] = 0;
    for (i=0; i<n; ++i) ws[x[i]=r[i]]++;
    for (i=1; i<m; ++i) ws[i] += ws[i-1];
    for (i=n-1; i>=0; --i) sa[--ws[x[i]]] = i;
    for (j=1, p=1; j<n; j*=2, m=p) {
        for (p=0, i=n-j; i<n; ++i) y[p++] = i;
        for (i=0; i<n; ++i) if (sa[i] >= j) y[p++] = sa[i] - j;
        for (i=0; i<n; ++i) wv[i] = x[y[i]];
        for (i=0; i<m; ++i) ws[i] = 0;
        for (i=0; i<n; ++i) ws[wv[i]]++;
        for (i=1; i<m; ++i) ws[i] += ws[i-1];
        for (i=n-1; i>=0; --i) sa[--ws[wv[i]]] = y[i];
        for (t=x, x=y, y=t, p=1, x[sa[0]]=0, i=1; i<n; ++i)
            x[sa[i]] = cmp(y, sa[i-1], sa[i], j) ? p-1 : p++;
    }
}

void calheight(int *r, int *sa, int n) {
    int i, j, k = 0;

    for (i=1; i<=n; ++i) rank[sa[i]] = i;
    for (i=0; i<n; height[rank[i++]]=k)
        for (k? --k:0, j=sa[rank[i]-1]; r[i+k]==r[j+k]; ++k)
            /*do nothing*/;
}

int getRepeat(int len, int n) {
    int i, maxx, minn;
    int ret = 0;

    maxx = -1;
    minn = INF;

    for (i=1; i<=n; ++i) {
        if (height[i] >= len) {
            maxx = max(sa[i], max(sa[i-1], maxx));
            minn = min(sa[i], min(sa[i-1], minn));
        } else {
            if (maxx!=-1 && minn!=INF && (maxx-minn)>=len)
                ++ret;
            maxx = -1;
            minn = INF;
        }
    }

    if (maxx!=-1 && minn!=INF && (maxx-minn)>=len)
        ++ret;

    return ret;
}

void printRank(int n) {
    int i;

    printf("print rank...
");
    for (i=1; i<=n; ++i)
        printf("%d ", rank[i]);
    printf("
");
}

void printHeight(int n) {
    int i;

    printf("print height...
");
    for (i=1; i<=n; ++i)
        printf("%d ", height[i]);
    printf("
");
}

void printSa(int n) {
    int i;

    printf("print sa...
");
    for (i=0; i<=n; ++i)
        printf("%d ", sa[i]);
    printf("
");
}

int main() {
    int i, len;
    int ans;

#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    while (scanf("%s",s)!=EOF && (s[0]!='#')) {
        //printf("%s
", s);
        for (i=0; s[i]; ++i)
            str[i] = s[i] - 'a' + 1;
        str[i] = 0;
        len = i;
        da(str, sa, len+1, MAXM);
        calheight(str, sa, len);
#ifndef ONLINE_JUDGE
        printSa(len);
        printRank(len);
        printHeight(len);
#endif
        for (ans=0, i=1; i<=len/2; ++i) {
            ans += getRepeat(i, len);
        }
        printf("%d
", ans);
    }

    return 0;
}