P1253 扶苏的问题

link

非常直白的线段树题目

要注意负数的问题以及吮吸

#include<iostream>
#include<cstring>
#include<cstdio>
#define int long long
using namespace std;
int tree[8000002];
int lazyre[8000002];
int lazyad[8000002];
int n,q;
int op;
int minn;
int x,y,z;
void pushdown(int root,int l,int r){
	if(lazyre[root]!=minn){
		lazyad[root<<1]=0;
		lazyad[root<<1|1]=0;
		lazyre[root<<1]=lazyre[root];
		lazyre[root<<1|1]=lazyre[root];
		tree[root<<1]=tree[root<<1|1]=lazyre[root];
		lazyre[root]=minn;
	}
	if(lazyad[root]!=0){
		lazyad[root<<1]+=lazyad[root];
		lazyad[root<<1|1]+=lazyad[root];
		tree[root<<1]+=lazyad[root];
		tree[root<<1|1]+=lazyad[root];
		lazyad[root]=0;
	}
	
}
void pushup(int root){
	tree[root]=max(tree[root<<1],tree[root<<1|1]);
}
void add(int root,int l,int r,int L,int R,int v){
	if(L<=l&&r<=R){
		lazyad[root]+=v;
		tree[root]+=v;
		return ;
	}
	pushdown(root,l,r);
	int mid=(l+r)>>1;
	if(L<=mid) add(root<<1,l,mid,L,R,v);
	if(R>mid) add(root<<1|1,mid+1,r,L,R,v);
	pushup(root);
}
void re(int root,int l,int r,int L,int R,int v){
	if(L<=l&&r<=R){
		lazyad[root]=0;
		lazyre[root]=v;
		tree[root]=v;
		return ;
	}
	int mid=(l+r)>>1;
	pushdown(root,l,r);
	if(L<=mid) re(root<<1,l,mid,L,R,v);
	if(R>mid) re(root<<1|1,mid+1,r,L,R,v);
	pushup(root);
}
int ask(int root,int l,int r,int L,int R){
	if(L<=l&&r<=R){
		return tree[root];
	}
	pushdown(root,l,r);
	int mid=(l+r)>>1;
	int ans=minn;
	if(L<=mid) ans=max(ans,ask(root<<1,l,mid,L,R));
	if(R>mid) ans=max(ans,ask(root<<1|1,mid+1,r,L,R));
	pushup(root);
	return ans;
}
signed main(){
	scanf("%lld%lld",&n,&q);
	memset(lazyre,0xc0,sizeof(lazyre));
	minn=lazyre[0];
	//cout<<minn;
	for(int i=1;i<=n;++i){
		scanf("%lld",&x);
		add(1,1,n,i,i,x);
	}
	for(int i=1;i<=q;++i){
		scanf("%lld",&op);
		if(op==1){
			scanf("%lld%lld%lld",&x,&y,&z);
			re(1,1,n,x,y,z);
		}
		if(op==2){
			scanf("%lld%lld%lld",&x,&y,&z);
			add(1,1,n,x,y,z);
		}
		if(op==3){
			scanf("%lld%lld",&x,&y);
			cout<<ask(1,1,n,x,y)<<endl;
		}
	}
}