【Codeforces】补题合集

Educational Codeforces Round 143 (Rated for Div. 2)

A. Two Towers

拼接序列。枚举相邻相同字母。如果 \(>1\) 则无解。否则可以做一个断点，有解。

点击查看代码

// Problem: A. Two Towers
// Contest: Codeforces - Educational Codeforces Round 143 (Rated for Div. 2)
// URL: https://codeforces.com/contest/1795/problem/A
// Memory Limit: 256 MB
// Time Limit: 2000 ms
// 
// Powered by CP Editor (https://cpeditor.org)
 
#include <bits/stdc++.h>
using namespace std;
 
#define Multicase() for(int T = read() ; T ; T--)
#define lowbit(x) (x & (-x))
#define ls(p) (p<<1)
#define rs(p) (p<<1|1)
#define l(p) tree[p].ls
#define r(p) tree[p].rs
#define sum(p) tree[p].sum
#define tag(p) tree[p].tag
#define F(i,a,b) for(int i=(a) ;i<=(b);++i)
#define F2(i,a,b) for(int i=(a);i< (b);++i)
#define dF(i,a,b) for(int i=(a);i>=(b);--i)
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define Debug debug("Passing [%s] in LINE %d\n",__FUNCTION__,__LINE__)
#define clr(a,x) memset(a,x,sizeof(a))
#define pb push_back
#define mkp make_pair
#define fi first
#define se second
#define endl '\n'
#define ENDL putchar('\n')
#define forGraph(u) for(int i=head[u];i;i=G[i].next)
 
const int N=5e5+5;
const int M=1e6+5;
const int MN=1e3+5;
const int iinf=INT_MAX;
const double eps=1e-9;
const double pi=acos(-1);
const long long linf=LLONG_MAX;
const long long mod=1000000007,mod2=998244353;
 
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef map<int,int> mii;
typedef map<ll,ll> mll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef map<string,int> msi;
 
inline int read(){int x(0), f(0); char ch=getchar(); while(ch<'0'||ch>'9'){f|=ch=='-';ch=getchar();} while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48); ch=getchar();} return f?-x:x;}
template <typename T> void read(T &x){x=0; T f(0); char ch=getchar(); while(ch<'0'||ch>'9'){f|=ch=='-';ch=getchar();} while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48); ch=getchar();} x=f?-x:x;}
template <typename T,typename ...Arg>void read(T& x,Arg& ...arg){read(x);read(arg...);}
template <typename T> inline void write(T x){static char buf[64]; static int tot(0); if(x<0) putchar('-'),x=-x; do buf[++tot]=(x%10)+48,x/=10; while(x); do putchar(buf[tot--]); while(tot);}
template <typename T> void write(T x,char c){static char buf[64]; static int tot(0); if(x<0) putchar('-'),x=-x; do buf[++tot]=(x%10)+48,x/=10; while(x); do putchar(buf[tot--]); while(tot); putchar(c);}
void judge(bool x){printf(x?"YES\n":"NO\n");}
 
void Solve();
 
struct Graph{
    int to,w,next;
}G[M<<1];
int head[N],cnt;
void addEdge(int u,int v,int w=1){G[++cnt]=(Graph){v,w,head[u]}; head[u]=cnt;}
 
template<class T,class U> void chkmax(T &x, U y) { if(x < y) x = y; }
template<class T,class U> void chkmin(T &x, U y) { if(x > y) x = y; }
 
int n,m,q,k,p;
int a[N],b[N],f[N];
vector<int> v;
 
int main(){
    Multicase()
        Solve();
}
 
string s,t;
 
void Solve(){
	p=0;
	read(n,m);
	cin>>s>>t;
	reverse(t.begin(),t.end());
	s+=t;
	F(i,1,n+m-1) if(s[i]==s[i-1]) p++;
	if(p<=1) judge(1);
	else judge(0);
}

B. Ideal Point

典中典之线段交集。先把不包含 \(k\) 的全去了，然后扫一遍，看看被每个线段都覆盖的点是否只有 \(k\) 一个即可。

点击查看代码

// Problem: B. Ideal Point
// Contest: Codeforces - Educational Codeforces Round 143 (Rated for Div. 2)
// URL: https://codeforces.com/contest/1795/problem/B
// Memory Limit: 256 MB
// Time Limit: 2000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
using namespace std;

#define Multicase() for(int T = read() ; T ; T--)
#define lowbit(x) (x & (-x))
#define ls(p) (p<<1)
#define rs(p) (p<<1|1)
#define l(p) tree[p].ls
#define r(p) tree[p].rs
#define sum(p) tree[p].sum
#define tag(p) tree[p].tag
#define F(i,a,b) for(int i=(a) ;i<=(b);++i)
#define F2(i,a,b) for(int i=(a);i< (b);++i)
#define dF(i,a,b) for(int i=(a);i>=(b);--i)
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define Debug debug("Passing [%s] in LINE %d\n",__FUNCTION__,__LINE__)
#define clr(a,x) memset(a,x,sizeof(a))
#define pb push_back
#define mkp make_pair
#define fi first
#define se second
#define endl '\n'
#define ENDL putchar('\n')
#define forGraph(u) for(int i=head[u];i;i=G[i].next)

const int N=5e5+5;
const int M=1e6+5;
const int MN=1e3+5;
const int iinf=INT_MAX;
const double eps=1e-9;
const double pi=acos(-1);
const long long linf=LLONG_MAX;
const long long mod=1000000007,mod2=998244353;

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef map<int,int> mii;
typedef map<ll,ll> mll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef map<string,int> msi;

inline int read(){int x(0), f(0); char ch=getchar(); while(ch<'0'||ch>'9'){f|=ch=='-';ch=getchar();} while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48); ch=getchar();} return f?-x:x;}
template <typename T> void read(T &x){x=0; T f(0); char ch=getchar(); while(ch<'0'||ch>'9'){f|=ch=='-';ch=getchar();} while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48); ch=getchar();} x=f?-x:x;}
template <typename T,typename ...Arg>void read(T& x,Arg& ...arg){read(x);read(arg...);}
template <typename T> inline void write(T x){static char buf[64]; static int tot(0); if(x<0) putchar('-'),x=-x; do buf[++tot]=(x%10)+48,x/=10; while(x); do putchar(buf[tot--]); while(tot);}
template <typename T> void write(T x,char c){static char buf[64]; static int tot(0); if(x<0) putchar('-'),x=-x; do buf[++tot]=(x%10)+48,x/=10; while(x); do putchar(buf[tot--]); while(tot); putchar(c);}
void judge(bool x){printf(x?"YES\n":"NO\n");}

void Solve();

struct Graph{
    int to,w,next;
}G[M<<1];
int head[N],cnt;
void addEdge(int u,int v,int w=1){G[++cnt]=(Graph){v,w,head[u]}; head[u]=cnt;}

template<class T,class U> void chkmax(T &x, U y) { if(x < y) x = y; }
template<class T,class U> void chkmin(T &x, U y) { if(x > y) x = y; }

int n,m,q,k,p;
int a[N],b[N],f[N];
vector<pii> seg;

int main(){
    Multicase()
        Solve();
}

void Solve(){
	vector<pii> ().swap(seg);
	read(n,k);
	F(i,1,n){
		int l,r;
		read(l,r);
		if(l>k || r<k) continue;
		else seg.pb(mkp(l,r));
	}
	int L=-iinf,R=iinf;
	for(auto it:seg){
		L=max(L,it.fi);
		R=min(R,it.se);
	}
	if(L==k && R==k) judge(1);
	else judge(0);
}