C++-POJ2777-Count Color[线段树][lazy标记][区间修改]

 分析：https://www.bilibili.com/read/cv4777102

 #include <cstdio>
 #include <algorithm>
 using namespace std;
 const int MAXN=1e5+;
 struct node{int l,r,lazy,color;}t[MAXN*];
 int L,R,C,n,m,q;
 #define ls t[x].l
 #define rs t[x].r
 int count(int x){int ans=;for(;x;x>>=)if(x&)ans++;return ans;}
 void pushdown(int x){if(t[x].lazy)t[ls].lazy=t[rs].lazy=t[ls].color=t[rs].color=t[x].lazy,t[x].lazy=;}
 void update(int x){t[x].color=t[ls].color|t[rs].color;}
 void build(int x,int l,int r){
     if(l==r){t[x].color=;return;}
     int mid=(l+r)>>;t[x].l=(x<<),t[x].r=(x<<|);
     build(ls,l,mid),build(rs,mid+,r),update(x);
 }
 void update(int x,int l,int r){
     if(L<=l&&r<=R){t[x].color=t[x].lazy=<<(C-);return;}
     pushdown(x);int mid=(l+r)>>;
     if(L<=mid)update(ls,l,mid);
     if(R>mid)update(rs,mid+,r);
     update(x);
 }
 int query(int x,int l,int r){
     if(L<=l&&r<=R)return t[x].color;
     pushdown(x);int mid=(l+r)>>,ans=;
     if(L<=mid)ans|=query(ls,l,mid);
     if(R>mid)ans|=query(rs,mid+,r);
     return ans;
 }
 int main(){
     scanf("%d%d%d",&n,&m,&q),build(,,n);
     for(int a,b;q--;){
         char s[];scanf("%s",s);
         if(s[]=='C')scanf("%d%d%d",&a,&b,&C),L=min(a,b),R=max(a,b),update(,,n);
         else scanf("%d%d",&a,&b),L=min(a,b),R=max(a,b),printf("%d\n",count(query(,,n)));
     }
     return ;
 }