经典区间染色板子题

#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int N = 1e6+10;
struct Segment{int l,r,id;
}tr[N<<2];
int n,color,m;void pushdown(int u){if(tr[u].id){tr[u<<1].id = tr[u<<1|1].id = tr[u].id;tr[u].id = 0;}
}void build(int u,int l,int r){tr[u] = {l,r,1};if(l==r)return;int mid = l+r>>1;build(u<<1,l,mid),build(u<<1|1,mid+1,r);
}void modify(int u,int l,int r,int c){if(tr[u].l>=l&&tr[u].r<=r){tr[u].id = c;return;}pushdown(u);int mid = tr[u].l+tr[u].r>>1;if(l<=mid)modify(u<<1,l,r,c);if(r>mid)modify(u<<1|1,l,r,c);
}int query(int u,int l,int r){if(tr[u].id)return tr[u].id;int res = 0;int mid = tr[u].l+tr[u].r>>1;if(l<=mid)res|=query(u<<1,l,r);if(r>mid)res|=query(u<<1|1,l,r);return res;
}
int lowbit(int x){return x&-x;}int cal(int x){int res = 0;for(int i=x;i;i-=lowbit(i))res++;return res;
}int main()
{ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);cin>>n>>color>>m;build(1,1,n);while(m--){char op;int l,r,c;cin>>op>>l>>r;if(l>r)swap(l,r);if(op=='C'){cin>>c;modify(1,l,r,1<<(c-1));}else cout<<cal(query(1,l,r))<<"\n";}}