题目链接:https://cn.vjudge.net/contest/318888#problem/C
题意:给定一个字符串,求不相同的子串个数。
思路:
感觉就是记住这个公式吧。。至于怎么推出来的我也不知道。。。。 如果有大佬知道怎么推出来的欢迎在底下给我留言
但是这里有一个点需要小心:
因为我们求后缀数组的时候为了防止越界的问题的话,会让最后一个为0(一个最小的从未出现的值)。这样的话我们的末尾会多一个0,所以如果是这样我们推出来的公式应该是
(n-1)-sa[k]+1-height[k]
1 #include <stdio.h> 2 #include <iostream> 3 #include <algorithm> 4 #include <string.h> 5 #include <stdlib.h> 6 #include <math.h> 7 #include <queue> 8 #include <set> 9 10 #define INF 0x3f3f3f3f 11 #define pii pair<int,int> 12 #define LL long long 13 typedef unsigned long long ull; 14 using namespace std; 15 const int maxn = 1e5+10; 16 17 18 char s[maxn]; 19 int sa[maxn],t[maxn],t2[maxn],c[maxn]; 20 int height[maxn],Rank[maxn]; 21 22 void build_sa(int n,int m){ 23 int i,*x = t,*y = t2; 24 for (i=0;i<m;i++){ 25 c[i] = 0; 26 } 27 for (i=0;i<n;i++){ 28 c[x[i] = s[i]]++; 29 } 30 for (i=1;i<m;i++){ 31 c[i] += c[i-1]; 32 } 33 for (i=n-1;i>=0;i--){ 34 sa[--c[x[i]]] = i; 35 } 36 for (int k=1;k<=n;k<<=1){ 37 int p = 0; 38 for (i=n-k;i<n;i++){ 39 y[p++] = i; 40 } 41 for (i=0;i<n;i++){ 42 if (sa[i]>=k) 43 y[p++] = sa[i]-k; 44 } 45 for (i=0;i<m;i++){ 46 c[i] = 0; 47 } 48 for (i=0;i<n;i++){ 49 c[x[y[i]]]++; 50 } 51 for (i=1;i<m;i++){ 52 c[i] += c[i-1]; 53 } 54 for (i=n-1;i>=0;i--){ 55 sa[--c[x[y[i]]]] = y[i]; 56 } 57 swap(x,y); 58 p = 1; 59 x[sa[0]] = 0; 60 for (i=1;i<n;i++){ 61 x[sa[i]] = y[sa[i-1]]==y[sa[i]] && y[sa[i-1]+k]==y[sa[i]+k]?p-1:p++; 62 } 63 if (p>=n) 64 break; 65 m = p; 66 } 67 } 68 69 void getHeight(int n){ 70 int i,j,k=0; 71 for (i=1;i<=n;i++){ 72 Rank[sa[i]] = i; 73 } 74 for (i=0;i<n;i++){ 75 if (k) 76 k--; 77 j = sa[Rank[i]-1]; 78 while (s[i+k] == s[j+k]) 79 k++; 80 height[Rank[i]] = k; 81 } 82 } 83 84 void solve(int n){ 85 int ans = 0; 86 for (int i=1;i<=n;i++){ 87 ans += n-sa[i]-height[i]; 88 } 89 printf("%d\n",ans); 90 } 91 92 93 int main(){ 94 int T; 95 scanf("%d",&T); 96 while (T--){ 97 scanf("%s",s); 98 int len = strlen(s); 99 build_sa(len+1,200); 100 getHeight(len); 101 solve(len); 102 } 103 return 0; 104 }
1 #include <stdio.h> 2 #include <iostream> 3 #include <algorithm> 4 #include <string.h> 5 #include <stdlib.h> 6 #include <math.h> 7 #include <queue> 8 #include <set> 9 10 #define INF 0x3f3f3f3f 11 #define pii pair<int,int> 12 #define LL long long 13 using namespace std; 14 typedef unsigned long long ull; 15 const int MAXN = 2e5 + 10; 16 17 int wa[MAXN], wb[MAXN], wv[MAXN], ws_[MAXN]; 18 int sta[MAXN]; 19 int cnt[MAXN]; 20 void Suffix(int *r, int *sa, int n, int m) 21 { 22 int i, j, k, *x = wa, *y = wb, *t; 23 for(i = 0; i < m; ++i) ws_[i] = 0; 24 for(i = 0; i < n; ++i) ws_[x[i] = r[i]]++; 25 for(i = 1; i < m; ++i) ws_[i] += ws_[i - 1]; 26 for(i = n - 1; i >= 0; --i) sa[--ws_[x[i]]] = i; 27 for(j = 1, k = 1; k < n; j *= 2, m = k) 28 { 29 for(k = 0, i = n - j; i < n; ++i) y[k++] = i; 30 for(i = 0; i < n; ++i) if(sa[i] >= j) y[k++] = sa[i] - j; 31 for(i = 0; i < n; ++i) wv[i] = x[y[i]]; 32 for(i = 0; i < m; ++i) ws_[i] = 0; 33 for(i = 0; i < n; ++i) ws_[wv[i]]++; 34 for(i = 1; i < m; ++i) ws_[i] += ws_[i - 1]; 35 for(i = n - 1; i >= 0; --i) sa[--ws_[wv[i]]] = y[i]; 36 t = x; 37 x = y; 38 y = t; 39 for(x[sa[0]] = 0, i = k = 1; i < n; ++i) 40 x[sa[i]] = (y[sa[i - 1]] == y[sa[i]] && y[sa[i - 1] + j] == y[sa[i] + j]) ? k - 1 : k++; 41 } 42 } 43 int Rank[MAXN], height[MAXN], sa[MAXN], r[MAXN]; 44 char s[MAXN]; 45 int indexx[MAXN],vis[200]; 46 void calheight(int *r,int *sa,int n) 47 { 48 int i,j,k=0; 49 for(i=1; i<=n; i++)Rank[sa[i]]=i; 50 for(i=0; i<n; height[Rank[i++]]=k) 51 for(k?k--:0,j=sa[Rank[i]-1]; r[i+k]==r[j+k]; k++); 52 } 53 54 bool check(int x,int n,int k){ 55 int tot = 1; 56 for (int i=1;i<n;i++){ 57 if (height[i]>=x){ 58 tot++; 59 } 60 else { 61 if (tot>=k) 62 return true; 63 tot = 1; 64 } 65 } 66 return tot>=k; 67 } 68 69 70 71 int main(){ 72 int T; 73 scanf("%d",&T); 74 while (T--){ 75 scanf("%s",s); 76 int n = strlen(s); 77 for (int i=0;i<n;i++){ 78 r[i] = s[i]; 79 } 80 r[n] = 0; 81 Suffix(r,sa,n+1,300); 82 calheight(r,sa,n); 83 LL ans = 0; 84 for (int i=1;i<=n;i++){ 85 ans += (n-sa[i]-height[i]); 86 } 87 printf("%lld\n",ans); 88 } 89 return 0; 90 }