查询回文子串个数:
#include<bits/stdc++.h> using namespace std; typedef long long LL; typedef pair<double,int> pii; const int N = 3e5+5; const int M = 1e6+5; const LL Mod = 1e9+7; #define rg register #define pi acos(-1) #define INF 1e18 #define CT0 cin.tie(0),cout.tie(0) #define IO ios::sync_with_stdio(false) #define dbg(ax) cout << "now this num is " << ax << endl; namespace FASTIO{ inline LL read(){ LL x = 0,f = 1;char c = getchar(); while(c < '0' || c > '9'){if(c == '-') f = -1;c = getchar();} while(c >= '0' && c <= '9'){x = (x<<1)+(x<<3)+(c^48);c = getchar();} return x*f; } void print(int x){ if(x < 0){x = -x;putchar('-');} if(x > 9) print(x/10); putchar(x%10+'0'); } } using namespace FASTIO; int len[N]; int Marchar(string t) { string s = "@#"; int mx = 0,cnt = 0,p = 0; for(rg int i = 0;i < t.size();++i) { s += "#"; s += t[i]; } s += "#"; for(rg int i = 0;i < s.size();++i) { if(mx > i) len[i] = min(mx-i,len[2*p-i]); else len[i] = 1; while(s[i-len[i]] == s[i+len[i]]) len[i]++; if(len[i]+i > mx) mx = len[i]+i,p = i; cnt += len[i]/2; } return cnt; } int main() { int n;n = read(); string s;cin >> s; int ans = Marchar(s); printf("%d\n",ans); system("pause"); return 0; }View Code