poj 2758 后缀数组

题意：
给一个字符串，提供两种操作，操作I：在 当前 第i个字符之前插入字符c；操作Q：求 原序列 后缀i，与后缀j的LCP，计算LCP时应把插入字符一起算上

思路：
确实没看出来这玩意能用后缀数组搞……
啊本题有好几个坑需要额外注意：
1. 插入时候的位置指的上当前序列；
2. 询问的位置指的是原序列，然后插入字符应计入比较；
3. 题目仅仅是说 Engligh Letter 而非 lower case letter，wa了半天才找到 - -|||；
4. I操作的步数非常少，最多200次
先抛开插入操作考虑询问操作，求一个序列任意两个后缀的LCP，显然后缀数组加RMQ，实现方式为对height数组做预处理，查询RMQ(rank[i],rank[j])；然后考虑插入，因为插入的操作数非常少，对于询问，可以先找到i和j的原序列LCP，再找到最近的一个插入在i，j后的字符距离i，j的位置k（这里找到最近的插入字符位置我是用set自带的平衡二叉树来加速查询），分情况讨论。
1. 如果LCP < k-1，显然插入字符对查询值无影响；
2. 如果LCP >= k-1，则从k位置开始，用t1，t2逐个指向当前序列中的字符，直至t1，,t2指向的均为原序列中的字符为止，然后递归查询t1，t2
本题在思路上不是特别麻烦，难点在看清题目的表述，以及实现能力上

#include <iostream>  #include <algorithm>  #include <stdio.h>  #include <string.h>  #include <vector>  #include <set>  using namespace std;  const int MAXINT  = 0x7fffffff;  const int MAXSIZE = 5 * 1e4 + 100;  vector<char> ins[MAXSIZE];  set<int> inset;  #define rep(i,n) for(int i = 0; i < n; i++)  int rk[MAXSIZE], sa[MAXSIZE], height[MAXSIZE], wa[MAXSIZE], res[MAXSIZE];  char w[MAXSIZE];  int len;  void getSa(int up) {      int *k = rk, *id = height, *r = res, *cnt = wa;      rep(i, up) cnt[i] = 0;      rep(i, len) cnt[k[i] = w[i]]++;      rep(i, up) cnt[i + 1] += cnt[i];      for (int i = len - 1; i >= 0; i--) {          sa[--cnt[k[i]]] = i;      }      int d = 1, p = 0;      while (p < len){          for (int i = len - d; i < len; i++) id[p++] = i;          rep(i, len)  if (sa[i] >= d) id[p++] = sa[i] - d;          rep(i, len) r[i] = k[id[i]];          rep(i, up) cnt[i] = 0;          rep(i, len) cnt[r[i]]++;          rep(i, up) cnt[i + 1] += cnt[i];          for (int i = len - 1; i >= 0; i--) {              sa[--cnt[r[i]]] = id[i];          }          swap(k, r);          p = 0;          k[sa[0]] = p++;          rep(i, len - 1) {              if (sa[i] + d < len && sa[i + 1] + d < len && r[sa[i]] == r[sa[i + 1]] && r[sa[i] + d] == r[sa[i + 1] + d])                  k[sa[i + 1]] = p - 1;              else k[sa[i + 1]] = p++;          }          if (p >= len) return;          d <<= 1, up = p, p = 0;      }  }  void getHeight() {      int i, k, h = 0;      rep(i, len) rk[sa[i]] = i;      rep(i, len) {          if (rk[i] == 0)              h = 0;          else {              k = sa[rk[i] - 1];              if (h) h--;              while (w[i + h] == w[k + h]) h++;          }          height[rk[i]] = h;      }  }  void getSuffix() {      len = strlen(w);      int up = 0;      rep(i, len) {          w[i] = w[i] - 'A' + 1;          up = up > w[i] ? up : w[i];      }      w[len] = 0;      getSa(up + 1);      getHeight();  }  int A[MAXSIZE];  int dmin[MAXSIZE][32];  void RMQ_init(int A[], int len){      //len 数组长度      for (int i = 0; i<len; ++i){          dmin[i][0] = A[i];      }      for (int j = 1; (1 << j) <= len; ++j)      for (int i = 0; i + (1 << j) - 1<len; ++i){          dmin[i][j] = min(dmin[i][j - 1], dmin[i + (1 << (j - 1))][j - 1]);      }      return;  }  int RMQ_min(int L, int R){      int k = 0;      while (1 << (k + 1) <= R - L + 1) k++;      return min(dmin[L][k], dmin[R - (1 << k) + 1][k]);  }  void sinsert(char c, int p){      bool flag = false;      int cnt = 0;      int k = -1;      for (int i = 0;i<len;++i){          if (cnt + ins[i].size() < p - 1) cnt += ins[i].size();          else{              k = p - cnt - 2;              if (ins[i].size() != 0){                  ins[i].push_back(ins[i][ins[i].size()-1]);                  for (int j = ins[i].size() - 1; j > k + 1; --j)                      ins[i][j] = ins[i][j-1];                  ins[i][k+1] = c;              }              else                  ins[i].push_back(c);              inset.insert(i);              //cout<<"Insert: "<<i<<endl;              flag = true;              break;          }          cnt++;      }      if (!flag){          if (cnt + ins[len].size() < p) ins[len].push_back(c);          else{              k = p - cnt - 2;              if (ins[len].size() != 0)                  for (int j = ins[len].size() - 1; j > k; --j)                      ins[len][j+1] = ins[len][j];              ins[len][k+1] = c;          }          inset.insert(len);          //cout<<"Insert: "<<len<<endl;      }  }  int query(int s1,int s2){      //cout<<"query: "<<s1<<" "<<s2<<endl;      int ans = 0;      if (s1 == s2){          for (int i = s1 + 1;i<len;++i){              ans+=ins[i].size();          }          ans += len-s1;          ans += ins[len].size();          return ans;      }      if (s1>s2) swap(s1,s2);      int lcp;      if (rk[s1] < rk[s2]) lcp = RMQ_min(rk[s1] + 1,rk[s2]);          else lcp = RMQ_min(rk[s2] + 1,rk[s1]);      ans = lcp;      //cout<<"RMQ_lcp: "<<ans<<endl;      int t = MAXINT;      set<int>::iterator t1 = inset.upper_bound(s1);      set<int>::iterator t2 = inset.upper_bound(s2);      if (t1!=inset.end())          t = t < *t1-s1 ? t : *t1-s1;      if (t2!=inset.end())          t = t < *t2-s2 ? t : *t2-s2;      //cout<<"t: "<<t<<endl;      if (lcp > t-1){          int i = s1 + t;          int j = s2 + t;          int i1 = 0, j1 = 0;          ans = t;          bool flag = true;          while (flag && (ins[j].size() != 0 || ins[i].size() != 0)){              char ic, jc;              if (i1 < ins[i].size()){                  ic = ins[i][i1];                  i1++;              }              else{                  if (i == len) {flag = false;break;}                  ic = w[i];                  i++;                  i1 = 0;              }              //cout<<"ic: "<<ic<<endl;              if (j1 < ins[j].size()){                  jc = ins[j][j1];                  j1++;              }              else{                  if (j == len) {flag = false;break;}                  jc = w[j];                  j++;                  j1 = 0;              }              //cout<<"jc: "<<jc<<endl;              if (ic == jc) ans++;              else flag = false;              //if (i == len || j == len) flag = false;          }          if (!flag) return ans;          else {              return ans+query(i,j);          }      }      else return ans;  }  int main(){      int a,b;      char temp[5];      scanf("%s",w);      getSuffix();      RMQ_init(height,len);      int n;      scanf("%d",&n);      for (int i=0;i<n;++i){          char c;          scanf("%s",temp);          if (temp[0] == 'Q'){              scanf("%d %d",&a,&b);              int ans = query(a-1,b-1);              printf("%d\n", ans);          }          else{              c = getchar();              c = getchar();              scanf("%d",&a);              sinsert(c - 'A' + 1,a);          }      }      return 0;  }