C Count New String
阿新 • • 發佈:2020-08-17
從後往前看,可以發現,當前字母是\(c\),當前位置\(p\),最多能影響到\(p'\),得到\([p,p']\)區間,把所有\(c\)字母影響區間合併在一起,可以得到\([L,R]<=[1,n]\),即每個字母最多影響長度為n的區間,所以我們把所以的字尾拿出來建立廣義字尾自動機(實際先建立tire樹)即可。
#include<iostream> #include<cstring> #include<algorithm> #include<cmath> #include<cstdlib> #include<climits> #include<stack> #include<vector> #include<queue> #include<set> #include<bitset> #include<map> //#include<regex> #include<cstdio> #include <iomanip> #pragma GCC optimize(2) #define up(i,a,b) for(int i=a;i<b;i++) #define dw(i,a,b) for(int i=a;i>b;i--) #define upd(i,a,b) for(int i=a;i<=b;i++) #define dwd(i,a,b) for(int i=a;i>=b;i--) //#define local typedef long long ll; typedef unsigned long long ull; const double esp = 1e-6; const double pi = acos(-1.0); const int INF = 0x3f3f3f3f; const int inf = 1e9; using namespace std; ll read() { char ch = getchar(); ll x = 0, f = 1; while (ch<'0' || ch>'9') { if (ch == '-')f = -1; ch = getchar(); } while (ch >= '0' && ch <= '9') { x = x * 10 + ch - '0'; ch = getchar(); } return x * f; } typedef pair<int, int> pir; #define lson l,mid,root<<1 #define rson mid+1,r,root<<1|1 #define lrt root<<1 #define rrt root<<1|1 const int N = 1e6 + 10; struct exsam { int len[N << 1]; int par[N << 1]; int trans[N << 1][11]; int tot = 1; int work(int p, int c) { int newq = ++tot; int q = trans[p][c]; len[newq] = len[p] + 1; par[newq] = par[q]; memcpy(trans[newq], trans[q], sizeof(trans[q])); par[q] = newq; for (; p&&trans[p][c] == q; p = par[p]) { trans[p][c] = newq; } return newq; } int ins(int p,int c) { if (trans[p][c]) { int q = trans[p][c]; if (len[p] + 1 == len[q])return q; else return work(p, c); } else { int now = ++tot; len[now] = len[p] + 1; for (; p && !trans[p][c]; p = par[p]) trans[p][c] = now; if (!p) { par[now] = 1; } else { int q = trans[p][c]; if (len[q] == len[p] + 1)par[now] = q; else par[now] = work(p, c); } return now; } } }sam; char s[N]; stack<pir>st; int pos[N]; int main() { scanf("%s", s + 1); int len = strlen(s + 1); st.push({ 11,len+1 }); pos[len + 1] = 1; dwd(i, len, 1) { int c = s[i] - 'a'; while (!st.empty() && st.top().first < c)st.pop(); pir t = st.top(); int last = pos[t.second]; dwd(j,t.second-1, i) { last = sam.ins(last, s[i] - 'a'); pos[j] = last; } st.push({ s[i] - 'a',i }); } ll ans = 0; upd(i, 2, sam.tot) { ans += sam.len[i] - sam.len[sam.par[i]]; } cout << ans << endl; }