UVa1608 UVaLive6258 Non-boring sequences

填坑系列(p.248)

比较神

从两端枚举

最坏复杂度就成O(nlogn)了

 #include<cstdio>
 #include<cstdlib>
 #include<algorithm>
 #include<iostream>
 #include<cstring>
 #include<string>

 using namespace std;

 void setIO(const string& a) {
     freopen((a + ".in").c_str(), "r", stdin);
     freopen((a + ".out").c_str(), "w", stdout);
 }

 template<typename Q> void read(Q& x) {
     static char c;
     static bool f;
     for(f = ; c = getchar(), !isdigit(c); ) if(c == '-') f = ;
     for(x = ; isdigit(c); c = getchar()) x = x *  + c - '';
     if(f) x = -x;
 }
 template<typename Q> Q read() {
     static Q x; read(x);
     return x;
 }

 const int N =  + ;

 int a[N], lp[N], rp[N];

 #include<map>
 map<int, int> cur;

 bool unique(int p, int l, int r) {
     return lp[p] < l && rp[p] > r;
 }

 bool check(int L, int R) {
     if(L >= R) return ;
     for(int k = ; L + k <= R - k; k++) {
         if(unique(L + k, L, R)) return check(L, L + k - ) && check(L + k + , R);
         if(unique(R - k, L, R)) return check(L, R - k - ) && check(R - k + , R);
     }
     return ;
 }

 int main() {
 #ifdef DEBUG
     freopen("in.txt", "r", stdin);
     freopen("out.txt", "w", stdout);
 #endif

     int T = read<int>();
     while(T--) {
         int n = read<int>();
         cur.clear();
         for(int i = ; i <= n; i++) {
             read(a[i]);
             if(cur.count(a[i])) lp[i] = cur[a[i]];
             else lp[i] = ;
             cur[a[i]] = i;
         }
         cur.clear();
         for(int i = n; i >= ; i--) {
             if(cur.count(a[i])) rp[i] = cur[a[i]];
             else rp[i] = n + ;
             cur[a[i]] = i;
         }
         puts(check(, n) ? "non-boring" : "boring");
     }

     return ;
 }