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SPOJ 694. Distinct Substrings,705. New Distinct Substrings(后缀数组)
题目大意:给定长度为N的字符串,求出其中不相同子串的个数。
解题思路:每一个字串一定是某个后缀的前缀,那么原问题就可以等价于求所有后缀之间的不相同的前缀的个数。如果所有的后缀按照suffix(sa[1]),suffix(sa[2])……suffix(sa[n])的顺序计算,我们会发现对于每个新加进来的后缀suffix(sa[k]),它将产生n-sa[k]+1个新的前缀。但是其中有leight[k]个是和前面的字符串的前缀是相同的。所以suffix(sa[k])加进来增加的不同的子串的个数为n-sa[k]+1-height[k]。累加起来就是所有字串的数目了。
705. New Distinct Substrings
Problem code: SUBST1
Given a string, we need to find the total number of its distinct substrings.
Input
T- number of test cases. T<=20;Each test case consists of one string, whose length is <= 50000
Output
For each test case output one number saying the number of distinct substrings.
Example
Input: 2 CCCCC ABABA Output: 5 9
#include <algorithm> #include <iostream> #include <stdlib.h> #include <string.h> #include <iomanip> #include <stdio.h> #include <string> #include <queue> #include <cmath> #include <stack> #include <ctime> #include <map> #include <set> #define eps 1e-9 ///#define M 1000100 ///#define LL __int64 #define LL long long ///#define INF 0x7ffffff #define INF 0x3f3f3f3f #define PI 3.1415926535898 #define zero(x) ((fabs(x)<eps)?0:x) #define mod 1000000007 #define Read() freopen("autocomplete.in","r",stdin) #define Write() freopen("autocomplete.out","w",stdout) #define Cin() ios::sync_with_stdio(false) using namespace std; inline int read() { char ch; bool flag = false; int a = 0; while(!((((ch = getchar()) >= '0') && (ch <= '9')) || (ch == '-'))); if(ch != '-') { a *= 10; a += ch - '0'; } else { flag = true; } while(((ch = getchar()) >= '0') && (ch <= '9')) { a *= 10; a += ch - '0'; } if(flag) { a = -a; } return a; } void write(int a) { if(a < 0) { putchar('-'); a = -a; } if(a >= 10) { write(a / 10); } putchar(a % 10 + '0'); } const int maxn = 50010; int wa[maxn], wb[maxn], wv[maxn], ws1[maxn]; int sa[maxn]; 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, p, *x = wa,*y = wb; for(i = 0; i<m; i++) ws1[i]=0; for(i = 0; i<n; i++) ws1[x[i]=r[i]]++; for(i = 1; i<m; i++) ws1[i]+=ws1[i-1]; for(i = n-1; i>=0; i--) sa[--ws1[x[i]]]=i; for(j = 1, p = 1; p<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++) ws1[i]=0; for(i = 0; i<n; i++) ws1[wv[i]]++; for(i = 1; i<m; i++) ws1[i]+=ws1[i-1]; for(i = n-1; i>=0; i--) sa[--ws1[wv[i]]]=y[i]; for(swap(x,y),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++; } return; } int rank[maxn],height[maxn]; 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++); return; } int sqe[maxn]; bool judge(int mid, int n) { int Max, Min; for(int i = 2; i <= n; i++) { Max = sa[i-1]; Min = sa[i-1]; while(height[i] >= mid) { Max = max(sa[i], Max); Min = min(sa[i], Min); i++; } if(Max - Min > mid) return true; } return false; } char str[maxn]; int main() { ///Cin(); int T; cin >>T; while(T--) { cin >>str; int len = strlen(str); for(int i = 0; i < len; i++) sqe[i] = str[i]; sqe[len] = 0; da(sqe, sa, len+1, 200); calheight(sqe, sa, len); int ans = 0; for(int i = 0; i < len; i++) ans += len-i-height[rank[i]]; cout<<ans<<endl; } return 0; }
SPOJ 694. Distinct Substrings,705. New Distinct Substrings(后缀数组)
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