线段树区间更新，区间求和，最大值，最小值模板

转自http://blog.csdn.net/acmer_ak/article/details/52002537

#include <string.h>
#include <algorithm>
#include <stdio.h>
#include <math.h>
#include <queue>
#define MAXN 100010
#define inf 0x3f3f3f3f  

using namespace std;  

struct node{
    int l,r;//区间[l,r]
    int add;//区间的延时标记
    int sum;//区间和
    int mx; //区间最大值
    int mn; //区间最小值
}tree[MAXN<<2];//一定要开到4倍多的空间  

void pushup(int index){
    tree[index].sum = tree[index<<1].sum+tree[index<<1|1].sum;
    tree[index].mx = max(tree[index<<1].mx,tree[index<<1|1].mx);
    tree[index].mn = min(tree[index<<1].mn,tree[index<<1|1].mn);
}
void pushdown(int index){
    //说明该区间之前更新过
    //要想更新该区间下面的子区间，就要把上次更新该区间的值向下更新
    if(tree[index].add > 0){
        //替换原来的值
        /*
        tree[index<<1].sum = (tree[index<<1].r-tree[index<<1].l+1)*tree[index].add;
        tree[index<<1|1].sum = (tree[index<<1|1].r-tree[index<<1|1].l+1)*tree[index].add;
        tree[index<<1].mx = tree[index].add;
        tree[index<<1|1].mx = tree[index].add;
        tree[index<<1].mn = tree[index].add;
        tree[index<<1|1].mn = tree[index].add;
        tree[index<<1].add = tree[index].add;
        tree[index<<1|1].add = tree[index].add;
        tree[index].add = 0;*/
        //在原来的值的基础上加上val  

        tree[index<<1].sum += (tree[index<<1].r-tree[index<<1].l+1)*tree[index].add;
        tree[index<<1|1].sum +=(tree[index<<1|1].r-tree[index<<1|1].l+1)*tree[index].add;
        tree[index<<1].mx += tree[index].add;
        tree[index<<1|1].mx += tree[index].add;
        tree[index<<1].mn += tree[index].add;
        tree[index<<1|1].mn += tree[index].add;
        tree[index<<1].add += tree[index].add;
        tree[index<<1|1].add += tree[index].add;
        tree[index].add = 0;  

    }
}
void build(int l,int r,int index){
    tree[index].l = l;
    tree[index].r = r;
    tree[index].add = 0;//刚开始一定要清0
    if(l == r){
        scanf("%d",&tree[index].sum);
        tree[index].mn = tree[index].mx = tree[index].sum;
        return ;
    }
    int mid = (l+r)>>1;
    build(l,mid,index<<1);
    build(mid+1,r,index<<1|1);
    pushup(index);
}
void updata(int l,int r,int index,int val){
    if(l <= tree[index].l && r >= tree[index].r){
        /*把原来的值替换成val,因为该区间有tree[index].r-tree[index].l+1
        个数，所以区间和 以及 最值为：
        */
        /*tree[index].sum = (tree[index].r-tree[index].l+1)*val;
        tree[index].mn = val;
        tree[index].mx = val;
        tree[index].add = val;//延时标记*/
        //在原来的值的基础上加上val,因为该区间有tree[index].r-tree[index].l+1
        //个数，所以区间和 以及 最值为：
        tree[index].sum += (tree[index].r-tree[index].l+1)*val;
        tree[index].mn += val;
        tree[index].mx += val;
        tree[index].add += val;//延时标记  

        return ;
    }
    pushdown(index);
    int mid = (tree[index].l+tree[index].r)>>1;
    if(l <= mid){
        updata(l,r,index<<1,val);
    }
    if(r > mid){
        updata(l,r,index<<1|1,val);
    }
    pushup(index);
}
int query(int l,int r,int index){
    if(l <= tree[index].l && r >= tree[index].r){
        //return tree[index].sum;
        return tree[index].mx;
        //return tree[index].mn;
    }
    pushdown(index);
    int mid = (tree[index].l+tree[index].r)>>1;
    int ans = 0;
    int Max = 0;
    int Min = inf;
    if(l <= mid){
        ans += query(l,r,index<<1);
        Max = max(query(l,r,index<<1),Max);
        Min = min(query(l,r,index<<1),Min);
    }
    if(r > mid){
        ans += query(l,r,index<<1|1);
        Max = max(query(l,r,index<<1|1),Max);
        Min = min(query(l,r,index<<1|1),Min);
    }
    //return ans;
    return Max;
    //return Min;
}
int main()
{
    int n,m,q,x,y,z;
    while(~scanf("%d%d",&n,&m)){
        build(1,n,1);
        while(m--){
            scanf("%d",&q);
            if(q == 1){
                cout<<"查询:(x,y)"<<endl;
                scanf("%d %d",&x,&y);
                cout<<query(x,y,1)<<endl;
            }
            else{
                cout<<"更新(x,y)为z："<<endl;
                scanf("%d %d %d",&x,&y,&z);
                updata(x,y,1,z);
                for(int i = 1; i <= n; ++i){
                    printf("a[%d] = %d\n",i,query(i,i,1));
                }
            }
        }
    }
    return 0;
}