【HDOJ】3518 Boring Counting

后缀数组2倍增可解。
  1 #include <cstdio>
  2 #include <cstring>
  3 #include <cstdlib>
  4 
  5 #define MAXN 1005
  6 #define INF 0xfffff
  7 #define MAXM 27
  8 
  9 int wa[MAXN], wb[MAXN], ws[MAXN], wv[MAXN];
 10 char s[MAXN];
 11 int str[MAXN], sa[MAXN];
 12 int height[MAXN], rank[MAXN];
 13 
 14 int max(int a, int b) {
 15     return a>b ? a:b;
 16 }
 17 
 18 int min(int a, int b) {
 19     return a<b ? a:b;
 20 }
 21 
 22 int cmp(int *r, int a, int b, int l) {
 23     return r[a]==r[b] && r[a+l]==r[b+l];
 24 }
 25 
 26 void da(int *r, int *sa, int n, int m) {
 27     int i, j, *x = wa, *y = wb, *t;
 28     int p;
 29 
 30     for (i=0; i<m; ++i) ws[i] = 0;
 31     for (i=0; i<n; ++i) ws[x[i]=r[i]]++;
 32     for (i=1; i<m; ++i) ws[i] += ws[i-1];
 33     for (i=n-1; i>=0; --i) sa[--ws[x[i]]] = i;
 34     for (j=1, p=1; j<n; j*=2, m=p) {
 35         for (p=0, i=n-j; i<n; ++i) y[p++] = i;
 36         for (i=0; i<n; ++i) if (sa[i] >= j) y[p++] = sa[i] - j;
 37         for (i=0; i<n; ++i) wv[i] = x[y[i]];
 38         for (i=0; i<m; ++i) ws[i] = 0;
 39         for (i=0; i<n; ++i) ws[wv[i]]++;
 40         for (i=1; i<m; ++i) ws[i] += ws[i-1];
 41         for (i=n-1; i>=0; --i) sa[--ws[wv[i]]] = y[i];
 42         for (t=x, x=y, y=t, p=1, x[sa[0]]=0, i=1; i<n; ++i)
 43             x[sa[i]] = cmp(y, sa[i-1], sa[i], j) ? p-1 : p++;
 44     }
 45 }
 46 
 47 void calheight(int *r, int *sa, int n) {
 48     int i, j, k = 0;
 49 
 50     for (i=1; i<=n; ++i) rank[sa[i]] = i;
 51     for (i=0; i<n; height[rank[i++]]=k)
 52         for (k? --k:0, j=sa[rank[i]-1]; r[i+k]==r[j+k]; ++k)
 53             /*do nothing*/;
 54 }
 55 
 56 int getRepeat(int len, int n) {
 57     int i, maxx, minn;
 58     int ret = 0;
 59 
 60     maxx = -1;
 61     minn = INF;
 62 
 63     for (i=1; i<=n; ++i) {
 64         if (height[i] >= len) {
 65             maxx = max(sa[i], max(sa[i-1], maxx));
 66             minn = min(sa[i], min(sa[i-1], minn));
 67         } else {
 68             if (maxx!=-1 && minn!=INF && (maxx-minn)>=len)
 69                 ++ret;
 70             maxx = -1;
 71             minn = INF;
 72         }
 73     }
 74 
 75     if (maxx!=-1 && minn!=INF && (maxx-minn)>=len)
 76         ++ret;
 77 
 78     return ret;
 79 }
 80 
 81 void printRank(int n) {
 82     int i;
 83 
 84     printf("print rank...
");
 85     for (i=1; i<=n; ++i)
 86         printf("%d ", rank[i]);
 87     printf("
");
 88 }
 89 
 90 void printHeight(int n) {
 91     int i;
 92 
 93     printf("print height...
");
 94     for (i=1; i<=n; ++i)
 95         printf("%d ", height[i]);
 96     printf("
");
 97 }
 98 
 99 void printSa(int n) {
100     int i;
101 
102     printf("print sa...
");
103     for (i=0; i<=n; ++i)
104         printf("%d ", sa[i]);
105     printf("
");
106 }
107 
108 int main() {
109     int i, len;
110     int ans;
111 
112 #ifndef ONLINE_JUDGE
113     freopen("data.in", "r", stdin);
114     freopen("data.out", "w", stdout);
115 #endif
116 
117     while (scanf("%s",s)!=EOF && (s[0]!='#')) {
118         //printf("%s
", s);
119         for (i=0; s[i]; ++i)
120             str[i] = s[i] - 'a' + 1;
121         str[i] = 0;
122         len = i;
123         da(str, sa, len+1, MAXM);
124         calheight(str, sa, len);
125 #ifndef ONLINE_JUDGE
126         printSa(len);
127         printRank(len);
128         printHeight(len);
129 #endif
130         for (ans=0, i=1; i<=len/2; ++i) {
131             ans += getRepeat(i, len);
132         }
133         printf("%d
", ans);
134     }
135 
136     return 0;
137 }