求出长度为1， 2， 3， 4， 5....的字符串最大出现次数 后缀数组 UVA 11855 - Buzzwords

题目链接

题意：给定一个文本，求出长度为1， 2， 3， 4， 5....的字符串最大出现次数，一直找到出现次数不大于1为止

思路：后缀数组，把空格去掉得到一个字符串，构造height数组，然后就是后缀数组的简单应用了，找连续一段最长的段并且都大于当前正在查找的长度

代码：

#include <cstdio>  #include <cstring>  #include <algorithm>  #include <string>  #include <iostream>  using namespace std;    const int MAXLEN = 1005;    struct Suffix {        int s[MAXLEN];      int sa[MAXLEN], t[MAXLEN], t2[MAXLEN], c[MAXLEN], n;      int rank[MAXLEN], height[MAXLEN];        void build_sa(int m) {      n++;      int i, *x = t, *y = t2;      for (i = 0; i < m; i++) c[i] = 0;      for (i = 0; i < n; i++) c[x[i] = s[i]]++;      for (i = 1; i < m; i++) c[i] += c[i - 1];      for (i = n - 1; i >= 0; i--) sa[--c[x[i]]] = i;      for (int k = 1; k <= n; k <<= 1) {          int p = 0;          for (i = n - k; i < n; i++) y[p++] = i;          for (i = 0; i < n; i++) if (sa[i] >= k) y[p++] = sa[i] - k;          for (i = 0; i < m; i++) c[i] = 0;          for (i = 0; i < n; i++) c[x[y[i]]]++;          for (i = 0; i < m; i++) c[i] += c[i - 1];          for (i = n - 1; i >= 0; i--) sa[--c[x[y[i]]]] = y[i];          swap(x, y);          p = 1; x[sa[0]] = 0;          for (i = 1; i < n; i++)          x[sa[i]] = (y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + k] == y[sa[i] + k]) ? p - 1 : p++;          if (p >= n) break;          m = p;      }      n--;      }        void getHeight() {      int i, j, k = 0;      for (i = 1; i <= n; i++) rank[sa[i]] = i;      for (i = 0; i < n; i++) {          if (k) k--;          int j = sa[rank[i] - 1];          while (s[i + k] == s[j + k]) k++;          height[rank[i]] = k;      }      }        void init(string str) {      n = 0;      for (int i = 0; i < str.length(); i++) if (str[i] != ' ')          s[n++] = str[i] - 'A' + 1;      s[n] = '\0';      }        void solve() {      build_sa(27);      getHeight();      int len = 1;      while (1) {          int ans = 1;          for (int i = 1; i <= n; i++) {          if (n - sa[i] < len) continue;          int cnt = 1;          while (i < n && height[i + 1] >= len) {              i++;              cnt++;          }          ans = max(ans, cnt);          }          if (ans == 1) break;          printf("%d\n", ans);          len++;      }      printf("\n");      }  } gao;    string str;    int main() {      while (getline(cin, str) && str != "") {      gao.init(str);      gao.solve();      }      return 0;  }