zoj 3453 Cupid's Sweet Bullet-优快云博客

本文链接：https://blog.youkuaiyun.com/waitfor_/article/details/7289099

本文介绍了一种简单线段树的实现方法，包括构建、查询和更新操作。该线段树支持区间修改和查找最大值等功能，适用于解决区间操作问题。

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简单线段树，成段更新

#include <cstdio>
#define con 100100
using namespace std;
int em[con],l[con],r[con],n;
struct Tree{
	int s;
	int t;
	int max;
	int add;
}tree[270010];
int max(int a,int b){
	return a>b?a:b;
}
void build(int s,int t,int id){
	tree[id].s=s;tree[id].t=t;
	tree[id].add=0;
	if(s==t){
		tree[id].max=em[s];
		return;
	}
	int mid=(tree[id].s+tree[id].t)>>1;
	build(s,mid,id*2);
	build(mid+1,t,id*2+1);
	tree[id].max=max(tree[id*2].max,tree[id*2+1].max);
}
int query(int s,int t,int aim,int id){
	if(s==t)
		return s;
	int mid=(tree[id].s+tree[id].t)>>1;
	if(tree[id].add!=0){
		tree[id*2].max+=tree[id].add;
		tree[id*2].add+=tree[id].add;
		tree[id*2+1].max+=tree[id].add;
		tree[id*2+1].add+=tree[id].add;
		tree[id].add=0;
	}
	if(tree[id*2+1].max>=aim)
		return query(mid+1,t,aim,id*2+1);
	else
		return query(s,mid,aim,id*2);
}
void update1(int s,int id){
	if(tree[id].s==s && tree[id].t==s){
		tree[id].max=1;
		return ;
	}
	int mid=(tree[id].s+tree[id].t)>>1;
	if(tree[id].add!=0){
		tree[id*2].max+=tree[id].add;
		tree[id*2].add+=tree[id].add;
		tree[id*2+1].max+=tree[id].add;
		tree[id*2+1].add+=tree[id].add;
		tree[id].add=0;
	}
	if(mid<s)
		update1(s,id*2+1);
	else
		update1(s,id*2);
	tree[id].max=max(tree[id*2].max,tree[id*2+1].max);
}
void update2(int s,int t,int aim,int id){
	if(tree[id].s==s && tree[id].t==t){
		tree[id].add+=aim;
		tree[id].max+=aim;
		return;
	}
	int mid=(tree[id].s+tree[id].t)>>1;
	if(tree[id].add!=0){
		tree[id*2].max+=tree[id].add;
		tree[id*2].add+=tree[id].add;
		tree[id*2+1].max+=tree[id].add;
		tree[id*2+1].add+=tree[id].add;
		tree[id].add=0;
	}
	if(s>mid)
		update2(s,t,aim,id*2+1);
	else if(t<=mid)
		update2(s,t,aim,id*2);
	else{
		update2(s,mid,aim,id*2);
		update2(mid+1,t,aim,id*2+1);
	}
	tree[id].max=max(tree[id*2].max,tree[id*2+1].max);
}
int main()
{
	int i,j;
	while(scanf("%d",&n)!=EOF){
		for(i=1;i<=n;i++){
			scanf("%d %d %d",&em[i],&l[i],&r[i]);
		}
		build(1,n,1);
		int m,tem;
		scanf("%d",&m);
		for(i=1;i<=m;i++){
			scanf("%d",&tem);
			if(tem>tree[1].max)
				update2(1,n,1,1);
			else{
				int per=query(1,n,tem,1);
				update1(per,1);
				update2(l[per],r[per],1,1);
			}
		}
		printf("%d\n",tree[1].max);
	}
}