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| #include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = a; i <= b; ++i)
#define ROF(i, a, b) for (int i = a; i >= b; --i)
#define SZ(x) ((int)x.size())
#define all(x,size) x.begin()+1,x.begin()+size+1
#define all1(x) x.begin(),x.end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef array<ll,3> arr;
typedef double DB;
const ll MAXN=static_cast<ll>(2e5)+10,MAXval=static_cast<ll>(1e18)+3;
int N,T;
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
cin>>N>>T;
vector<pll> wNode;
map<ll,ll> bHigh;
FOR(i, 1, T){
ll x,y;char c;
cin>>x>>y>>c;
if(c=='B'){
bHigh[x]=bHigh.find(x)==bHigh.end()?y:max(y,bHigh[x]);
}else{
wNode.push_back({x,y});
}
}
if(bHigh.empty()){
cout<<"Yes\n";
return 0;
}
ll maxHigh=0;
for(map<ll,ll>::reverse_iterator it=bHigh.rbegin();it!=bHigh.rend();++it){
it->second=max(it->second,maxHigh);
maxHigh=it->second;
}
FOR(i, 0, SZ(wNode)-1){
ll x=wNode[i].first,y=wNode[i].second;
map<ll,ll>::iterator it=bHigh.lower_bound(x);
if(it!=bHigh.end()){
ll yB=it->second;
if(yB>=y){
cout<<"No\n";
return 0;
}
}
}
cout<<"Yes\n";
return 0;
}
|
