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Time Limit: 6000/3000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 1848 Accepted Submission(s): 492
/* hdu 5008 查找字典序第k小的子串 problem: 给你一个字符串,每次寻找字典序第k小的子串(不同的)的开始,结尾坐标。 solve: 首先可以知道height本身就是按字典序来弄的,对于sa[i-1]和sa[i]而言只要减去 它们的公共部分即height[i],就是不同的子串. 可以借此处理出来[1,n]即到字典序第i大的后缀时总共有多少个不同的子串.然后 利用二分查找就能找到位置 还要注意就是当有多个的时候输出最小的位置,可以判断当前子串是否是公共前缀的 一部分.往后枚举找出最小的位置即可 a aa aaa 当你要找最小的串a时可能会找到 3 3.因为它也是aa,aaa的一部分,所以需要枚举一下 hhh-2016-08-12 19:24:38 */ #include <iostream> #include <vector> #include <cstring> #include <string> #include <cstdio> #include <queue> #include <algorithm> #include <functional> #include <map> #include <set> using namespace std; #define lson (i<<1) #define rson ((i<<1)|1) typedef long long ll; typedef unsigned int ul; const int INF = 0x3f3f3f3f; const int maxn = 100000+10; const int mod = 1e9+7; int t1[maxn],t2[maxn],c[maxn]; bool cmp(int *r,int a,int b,int l) { return r[a]==r[b] &&r[l+a] == r[l+b]; } void get_sa(int str[],int sa[],int Rank[],int height[],int n,int m) { n++; int p,*x=t1,*y=t2; for(int i = 0; i < m; i++) c[i] = 0; for(int i = 0; i < n; i++) c[x[i] = str[i]]++; for(int i = 1; i < m; i++) c[i] += c[i-1]; for(int i = n-1; i>=0; i--) sa[--c[x[i]]] = i; for(int j = 1; j <= n; j <<= 1) { p = 0; for(int i = n-j; i < n; i++) y[p++] = i; for(int i = 0; i < n; i++) if(sa[i] >= j) y[p++] = sa[i]-j; for(int i = 0; i < m; i++) c[i] = 0; for(int i = 0; i < n; i++) c[x[y[i]]]++ ; for(int i = 1; i < m; i++) c[i] += c[i-1]; for(int i = n-1; i >= 0; i--) sa[--c[x[y[i]]]] = y[i]; swap(x,y); p = 1; x[sa[0]] = 0; for(int i = 1; i < n; i++) x[sa[i]] = cmp(y,sa[i-1],sa[i],j)? p-1:p++; if(p >= n) break; m = p; } int k = 0; n--; for(int i = 0; i <= n; i++) Rank[sa[i]] = i; for(int i = 0; i < n; i++) { if(k) k--; int j = sa[Rank[i]-1]; while(str[i+k] == str[j+k]) k++; height[Rank[i]] = k; } } int Rank[maxn],height[maxn]; int sa[maxn]; char str[maxn]; int r[maxn]; ll num[maxn]; int lpos,rpos; int len ; void fin(ll x) { int l =1 ,r = len; int cur = 0; while(l <= r) { int mid = (l+r) >> 1; if(num[mid] >= x) { cur = mid; r = mid-1; } else l = mid+1; } // cout << "cur:" <<cur <<endl; x = x - num[cur-1]; lpos = sa[cur]+1; rpos = sa[cur]+height[cur]+x; int tlen = rpos-lpos+1; if(cur+1 <= len && tlen <= height[cur+1]) { for(int i = cur + 1; i <= len; i++) { if(height[i] >= tlen) { if(lpos > sa[i]+1) { lpos = sa[i]+1; rpos = lpos+tlen-1; } } else break; } } return ; } int main() { while(scanf("%s",str) != EOF) { len = strlen(str); for(int i = 0; i <len; i ++) { r[i] = str[i]; } r[len] = 0; num[0] = 0; get_sa(r,sa,Rank,height,len,200); for(int i = 1; i <= len; i++) { num[i] = (ll)(len - sa[i] - height[i]); num[i] += num[i-1]; } int n; ll x; scanf("%d",&n); lpos = 0,rpos = 0; for(int i = 1; i <= n; i++) { scanf("%I64d",&x); ll k = (ll)(lpos^rpos^x)+1LL; // cout << "k:" << k <<endl; lpos = rpos = 0; if(k > num[len]) { printf("0 0\n"); lpos = 0,rpos = 0; continue; } fin(k); printf("%d %d\n",lpos,rpos); } } return 0; }
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原文地址:http://www.cnblogs.com/Przz/p/5792183.html