HDU1754 I Hate It

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define inf 0x3f3f3f3f
#define lson l, m, rt << 1
#define rson m+1, r, rt << 1 | 1
const int maxn = 200005;
int A[maxn<<2], n, m, a, b;
char str[10];

void Max(int rt)
{
A[rt] = max(A[rt<<1], A[rt<<1 | 1]);
}

void Build(int l, int r, int rt)
{
if(l == r)
{
scanf("%d", &A[rt]);
return ;
}
int m = (l + r) >> 1;
Build(lson);
Build(rson);
Max(rt);
}

void Update(int p, int score, int l, int r, int rt)
{
if(l == r)
{
A[rt] = score;
return ;
}
int m = (l + r) >> 1;
if(p <= m) Update(p, score, lson);
else Update(p, score, rson);
Max(rt);
}

int Query(int ll, int rr, int l, int r, int rt)
{
if(ll <= l && rr >= r) return A[rt];
int m = (l + r) >> 1;
int max1 = -inf;
if(ll <= m) max1 = max(max1, Query(ll, rr, lson));
if(rr > m) max1 = max(max1, Query(ll, rr, rson));
return max1;
}

int main()
{
while(~scanf("%d %d", &n, &m))
{
Build(1, n, 1);
while(m--)
{
scanf("%s%d%d", str, &a, &b);
if(str[0] == 'Q')
{
int ans = Query(a, b, 1, n, 1);
printf("%d\n", ans);
}
else Update(a, b, 1, n, 1);
}
}
return  0;
}