HIHO #1078 : 线段树的区间修改

#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<string>
#include<cmath>
#include<queue>
#include<map>
#include<set>
#include<cstdlib>
#include<vector>
using namespace std;
#define cl(a,b) memset(a,b,sizeof(a))
#define LL long long
#define pb push_back
#define gcd __gcd

#define For(i,j,k) for(int i=(j);i<k;i++)
#define lowbit(i) (i&(-i))
#define _(x) printf("%d\n",x)

const int maxn = 1e5+10;
const int inf  = 1 << 28;

struct node{
LL sum;
int lazy;
}p[maxn<<2];

void push_up(int rt){
p[rt].sum = p[rt<<1].sum+p[rt<<1|1].sum;
}
void push_down(int rt,int l,int r){
if(p[rt].lazy==0)return ;
int mid = l+r>>1;
p[rt<<1].lazy = p[rt<<1|1].lazy = p[rt].lazy;
p[rt<<1].sum = (LL)(mid-l+1)*p[rt].lazy;
p[rt<<1|1].sum = (LL)(r-(mid+1)+1)*p[rt].lazy;
p[rt].lazy=0;
}

void build(int rt,int l,int r){
if(l==r){
scanf("%lld",&p[rt].sum);
return ;
}
p[rt].lazy = 0;
int mid = l+r>>1;
build(rt<<1,l,mid);
build(rt<<1|1,mid+1,r);
push_up(rt);
}

void updata(int rt,int l,int r,int x,int y,int v){
if(x<=l&&r<=y){
p[rt].lazy = v;
p[rt].sum = (LL)v*(r-l+1);
return ;
}
int mid = l+r>>1;
push_down(rt,l,r);
if(x<=mid) updata(rt<<1,l,mid,x,y,v);
if(y>mid) updata(rt<<1|1,mid+1,r,x,y,v);
push_up(rt);
}

LL query(int rt,int l,int r,int x,int y){
if(x<=l&&r<=y){
return p[rt].sum;
}
push_down(rt,l,r);
int mid = l+r>>1;
LL ans = 0;
if(x<=mid) ans+=query(rt<<1,l,mid,x,y);
if(y>mid)  ans+=query(rt<<1|1,mid+1,r,x,y);
return ans;
}

int main(){
int n;scanf("%d",&n);
build(1,1,n);
int m;scanf("%d",&m);
while(m--){
int t,x,y;
scanf("%d%d%d",&t,&x,&y);
if(t==0){
printf("%lld\n",query(1,1,n,x,y));
}
else{
int v;scanf("%d",&v);
updata(1,1,n,x,y,v);
}
}
return 0;
}