[洛谷P4070][SDOI2016]生成魔咒
阿新 • • 發佈:2018-12-22
題目大意:有一個字串,每次在末尾加入一個字元,問當前共有多少個本質不同的字串
題解:$SAM$,就是問插入這個字元後,多了多少個字串,就是當前這個點的$Right$陣列大小。
卡點:無
C++ Code:
#include <cstdio> #include <iostream> #include <map> #define maxn 100010 long long ans; namespace SAM { #define N (maxn << 1) #define root 1 int R[N], fail[N]; std::map<int, int> nxt[N]; int lst = root, idx = root; void append(int ch) { int p = lst, np = lst = ++idx; R[np] = R[p] + 1; for (; p && !nxt[p].count(ch); p = fail[p]) nxt[p][ch] = np; if (!p) fail[np] = root; else { int q = nxt[p][ch]; if (R[p] + 1 == R[q]) fail[np] = q; else { int nq = ++idx; nxt[nq] = nxt[q], fail[nq] = fail[q], R[nq] = R[p] + 1, fail[np] = fail[q] = nq; for (; p && nxt[p].count(ch) && nxt[p][ch] == q; p = fail[p]) nxt[p][ch] = nq; } } } int query() { return R[lst] - R[fail[lst]]; } #undef root #undef N } int n; int main() { std::ios::sync_with_stdio(false), std::cin.tie(0), std::cout.tie(0); std::cin >> n; for (int i = 0, x; i < n; i++) { std::cin >> x; SAM::append(x); std::cout << (ans += SAM::query()) << '\n'; } return 0; }