线段树模板

2017-08-30 19:53:27

writer：pprp

#include <bits/stdc++.h>

using namespace std;

#define MAXN 10000

struct Tree
{
    int val;//此区间存的值
    int addnum;//整个区间被增加的值
    bool lazy;//区间是否被整体修改过
    int lazy_chg;//区间被整体修改后的值(lazy==true时有效)
} tree[MAXN*4];

int arr[MAXN];//用于初始化的数组

int lson(int rt)
{
    return rt<<1;
}

int rson(int rt)
{
    return (rt<<1)|1;
}

//更新此区间存的值
//@param: rt:根的编号
void tree_update(int rt)
{
    tree[rt].val=max(tree[lson(rt)].val,tree[rson(rt)].val)+tree[rt].addnum;
    //可更改(max/min/sum)
}

//将编号rt的区间全变为val
//@param: 
void tree_chg(int left,int right,int rt,int val)
{
    tree[rt].val=val;/**可更改(求和则为v*(right-left+1))**/
    tree[rt].lazy=true;
    tree[rt].lazy_chg=val;
    tree[rt].addnum=0;
}

//将整体修改的信息向下传递
void pushDown(int left,int right,int rt)
{
    if(tree[rt].lazy)
    {
        tree[rt].lazy=false;
        int mid=(left+right)>>1;
        tree_chg(left,mid,lson(rt),tree[rt].lazy_chg);
        tree_chg(mid+1,right,rson(rt),tree[rt].lazy_chg);
    }
}

void tree_init()
{
    memset(tree,0,sizeof(tree));//清0
}

//建立一个线段树
void tree_build(int left,int right,int rt)//初始化维护某个数组
{
    tree[rt].lazy=false;
    tree[rt].addnum=0;
    if(left==right)
    {
        tree[rt].val=arr[left];/**需对应为原数组的名称**/
    }
    else
    {
        int mid=(left+right)>>1;
        tree_build(left,mid,lson(rt));
        tree_build(mid+1,right,rson(rt));
        tree_update(rt);
    }
}

//区间增加
//把l到r间的值都增加v
void tree_add(int left,int right,int rt,int l,int r,int val)
{
    if(l<=left&&right<=r)
    {
        tree[rt].val+=val;
        tree[rt].addnum+=val;
    }
    else
    {
        pushDown(left,right,rt);
        int mid=(left+right)>>1;
        if(l<=mid)tree_add(left,mid,lson(rt),l,r,val);
        if(r>mid)tree_add(mid+1,right,rson(rt),l,r,val);
        tree_update(rt);
    }
}

//区间修改
//把l到r间的值都修改为v
void tree_change(int left,int right,int rt,int l,int r,int v)
{
    if(l<=left&&right<=r)tree_chg(left,right,rt,v);
    else
    {
        pushDown(left,right,rt);
        int mid=(left+right)>>1;
        if(l<=mid)tree_change(left,mid,lson(rt),l,r,v);
        if(r>mid)tree_change(mid+1,right,rson(rt),l,r,v);
        tree_update(rt);
    }
}

//区间查询
//查询区间[l,r]维护的值
int tree_find(int left,int right,int rt,int l,int r,int val)
{
    if(l<=left&&right<=r)return tree[rt].val;
    else
    {
        pushDown(left,right,rt);
        int mid=(left+right)>>1;
        if(l<=mid&&r>mid)
            return max(tree_find(left,mid,lson(rt),l,r,val)
                       ,tree_find(mid+1,right,rson(rt),l,r,val));
        /**可更改(max/min/sum)**/
        if(l<=mid)return tree_find(left,mid,lson(rt),l,r,val);
        return tree_find(mid+1,right,rson(rt),l,r,val);
    }
}

int main()
{

    return 0;
}