大意: 给定序列$a$, $a_i$为偶数代表第$\frac{a_i}{2}$种左括号, 否则为第$\frac{a_i-1}{2}$种右括号. 询问区间是否是合法括号序列.
#include <iostream> #include <sstream> #include <algorithm> #include <cstdio> #include <math.h> #include <set> #include <map> #include <queue> #include <string> #include <string.h> #include <bitset> #include <unordered_map> #define REP(i,a,n) for(int i=a;i<=n;++i) #define PER(i,a,n) for(int i=n;i>=a;--i) #define hr putchar(10) #define pb push_back #define lc (o<<1) #define rc (lc|1) #define mid ((l+r)>>1) #define ls lc,l,mid #define rs rc,mid+1,r #define x first #define y second #define io std::ios::sync_with_stdio(false) #define endl '\n' #define DB(a) ({REP(__i,1,n) cout<<a[__i]<<' ';hr;}) using namespace std; typedef long long ll; typedef pair<int,int> pii; const int P = 1e9+7, P2 = 998244353, INF = 0x3f3f3f3f; ll gcd(ll a,ll b) {return b?gcd(b,a%b):a;} ll qpow(ll a,ll n) {ll r=1%P;for (a%=P;n;a=a*a%P,n>>=1)if(n&1)r=r*a%P;return r;} ll inv(ll x){return x<=1?1:inv(P%x)*(P-P/x)%P;} template <class T> void rd(T &x){x=0;bool f=0;char c=getchar();while(c<'0'||c>'9'){if(c=='-')f=1;c=getchar();}while('0'<=c&&c<='9'){x=x*10+c-'0';c=getchar();}if(f)x=-x;} //head const int N = 1e6+10; int n,m,q,a[N],s[N],L[N]; int main() { scanf("%d%d%d", &n, &m,&q); REP(i,1,n) scanf("%d",a+i); int top = 0; REP(i,1,n) { if (!top) s[++top] = i; else { if (a[i]/2==a[s[top]]/2&&a[i]==a[s[top]]+1) --top; else s[++top] = i; } L[i] = top; } REP(i,1,q) { int x, y; scanf("%d%d", &x, &y); puts((x-y&1)&&L[x-1]==L[y]?"YES":"NO"); } }