UVa 1608 Non-boring sequences (分治)
UVa Non 分治 sequences
2023-09-11 14:17:18 时间
题意:给你一个长度为n序列,如果这个任意连续子序列的中都有至少出现一次的元素,那么就称这个序列是不无聊的,判断这个序列是不是无聊的。
析:首先如果整个序列中有一个只出过一次的元素,假设是第 p 个,那么我就可以看他左边和右边的序列是不是不无聊,也就是判断 1~p-1 和 p+1 ~ n,这可以用分治来进行处理。
代码如下:
#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <cmath> #include <stack> #include <sstream> #include <list> #include <assert.h> #include <bitset> #define debug() puts("++++"); #define gcd(a, b) __gcd(a, b) #define lson l,m,rt<<1 #define rson m+1,r,rt<<1|1 #define fi first #define se second #define pb push_back #define sqr(x) ((x)*(x)) #define ms(a,b) memset(a, b, sizeof a) #define sz size() #define pu push_up #define pd push_down #define cl clear() #define all 1,n,1 #define FOR(x,n) for(int i = (x); i < (n); ++i) #define freopenr freopen("in.txt", "r", stdin) #define freopenw freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef unsigned long long ULL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const double inf = 1e20; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 200000 + 10; const LL mod = 1e9 + 7; const int dr[] = {-1, 0, 1, 0}; const int dc[] = {0, 1, 0, -1}; const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"}; int n, m; const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; inline bool is_in(int r, int c) { return r > 0 && r <= n && c > 0 && c <= m; } int a[maxn]; int l[maxn], r[maxn]; map<int, int> mp; bool dfs(int L, int R){ if(L >= R) return true; int t = R - L >> 1; for(int i = 0; i <= t; ++i){ if(l[i+L] < L && r[i+L] > R) return dfs(L, i+L-1) && dfs(i+1+L, R); if(l[R-i] < L && r[R-i] > R) return dfs(L, R-i-1) && dfs(R-i+1, R); } return false; } int main(){ int T; cin >> T; while(T--){ scanf("%d", &n); mp.cl; for(int i = 1; i <= n; ++i){ scanf("%d", a+i); if(mp.count(a[i])) l[i] = mp[a[i]]; else l[i] = 0; mp[a[i]] = i; } mp.cl; for(int i = n; i; --i){ if(mp.count(a[i])) r[i] = mp[a[i]]; else r[i] = n+1; mp[a[i]] = i; } puts(dfs(1, n) ? "non-boring" : "boring"); } return 0; }
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