线段树模板

//单点替换

#include <iostream>
#include <cstdio>
using namespace std;
const int maxn = 100005;
int  big[maxn*4];

void build(int l,int r,int rt)
{
if(l == r)
{
scanf("%d",&big[rt]);
return ;
}
int mid = (l+r)>>1;
build(l,mid,rt*2);
build(mid+1,r,rt*2+1);
big[rt] = max(big[rt*2],big[rt*2+1]);
}
void update(int p,int v,int l,int r,int rt)
{
if(l==r)
{
big[rt] = v;
return;
}
int mid = (l+r)>>1;
if(p<=mid) update(p,v,l,mid,rt*2);
else update(p,v,mid+1,r,rt*2+1);
big[rt]=max(big[rt*2],big[rt*2+1]);
}
int query(int b,int e,int l,int r,int rt)
{
if(b > r || e < l)
return -1;
if(b <= l && r<=e)
{
return big[rt];
}
int mid = (l+r)>>1;
int ans = 0;
if(b <= mid) ans = max(ans,query(b,e,l,mid,rt*2));
if(e > mid) ans = max(ans,query(b,e,mid+1,r,rt*2+1));
return ans;
}
int main()
{
int n,m;
while(scanf("%d%d",&n,&m)!=EOF)
{
build(1,n,1);
while(m--)
{
int a,b,e;
scanf("%d%d%d",&a,&b,&e);
if(a)
update(b,e,1,n,1);
else
printf("%d\n",query(b,e,1,n,1));
}
}
return 0;
}