线段树单点更新 区间求和，求最值

#include <iostream>#include <string.h>#include <algorithm>#include <stdio.h>#include <math.h>#include <queue>#define MAXN 100010#define inf 0x3f3f3f3fusing namespace std;struct node{    int l,r;//区间[l,r]    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 build(int l,int r,int index){    tree[index].l = l;    tree[index].r = r;    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 k,int index,int val){    if(tree[index].l == tree[index].r){        tree[index].sum = val;//把原来的值替换成val        //tree[index].sum += val;//在原来的值上加上val        tree[index].mn = tree[index].mx = tree[index].sum;        return ;    }    int mid = (tree[index].l+tree[index].r)>>1;    if(k <= mid){        updata(k,index<<1,val);    }    else{        updata(k,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;    }    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){                scanf("%d %d",&x,&y);                cout<<query(x,y,1)<<endl;            }            else{                scanf("%d %d",&x,&z);                updata(x,1,z);            }        }    }    return 0;}