hdu 1754 I Hate It（线段树，单点更新，区间最值）

#include <stdio.h>
#include <string.h>
#define TREE_SIZE (1 << (20))

//const int TREE_SIZE = 200000 + 10;

int max(int a, int b)
{
return a > b ? a : b;
}

int Cover[TREE_SIZE], Top[TREE_SIZE];

class IntervalTree
{
private:
int size;
int _Query(int a, int b, int l, int r, int Ind)
{
if (a <= l && b >= r)
return Top[Ind];
int mid = (l + r) >> 1, ret = Cover[Ind];
if (a <= mid)
ret = max(ret, _Query(a, b, l, mid, Ind << 1));
if (b > mid)
ret = max(ret, _Query(a, b, mid + 1, r, (Ind << 1) + 1));
return ret;
}
void _Modify(int a, int l, int r, int Ind, int d)
{
if (l == r && l == a)
{
Cover[Ind] = Top[Ind] = d;
return ;
}
int mid = (l + r) >> 1;
if (a <= mid)
_Modify(a, l, mid, Ind << 1, d);
else
_Modify(a, mid + 1, r, (Ind << 1) + 1, d);
Top[Ind] = max(Top[Ind << 1], Top[(Ind << 1 )+ 1]);
}
public:
IntervalTree()
{
memset(Cover, 0, sizeof(Cover));
memset(Top, 0, sizeof(Top));
size = (TREE_SIZE >> 2) - 1;
}
IntervalTree(int s)
{
memset(Cover, 0, sizeof(Cover));
memset(Top, 0, sizeof(Top));
size = s;
}
int Query(int a, int b)
{
return _Query(a, b, 1, size, 1);
}
void Modify(int a, int d)
{
return _Modify(a, 1, size, 1, d);
}
};

int main()
{
#ifdef LOCAL
freopen("in.txt", "r", stdin);
#endif // LOCAL
int n, m;
while (scanf("%d%d", &n, &m) == 2)
{
IntervalTree T(n);
for (int i = 1; i <= n; i++)
{
int tmp;
scanf("%d", &tmp);
T.Modify(i, tmp);
}
for (int i = 0; i < m; i++)
{
getchar();
char ch;
int a, b;
scanf("%c%d%d", &ch, &a, &b);
//printf("%c%d%d\n", ch,a,b);
if (ch == 'Q')
{
printf("%d\n", T.Query(a, b));
continue;
}
if (ch == 'U')
{
T.Modify(a, b);
continue;
}
}
}
return 0;
}

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <stack>
#include <vector>
#include <queue>
#include <map>
#include <climits>
#include <cassert>
#define LL long long
#define lson lo, mi, rt << 1
#define rson mi + 1, hi, rt << 1 | 1

using namespace std;
const int maxn = 200000 + 10;
const int inf = 0x3f3f3f3f;
const double eps = 1e-8;
const double pi = acos(-1.0);
const double ee = exp(1.0);

int maxPoint[maxn << 2];
void pushup(int rt)
{
maxPoint[rt] = max(maxPoint[rt << 1], maxPoint[rt << 1 | 1]);
}

void build(int lo, int hi, int rt)
{
if (lo == hi)
{
scanf("%d", &maxPoint[rt]);
return;
}
int mi = (lo + hi) >> 1;
build(lson);
build(rson);
pushup(rt);
}

void update(int pos, int num, int lo, int hi, int rt)
{
if (lo == hi)
{
maxPoint[rt] = num;
return;
}
int mi = (lo + hi) >> 1;
if (pos <= mi)
update(pos, num, lson);
else
update(pos, num, rson);
pushup(rt);
}

int query(int L, int H, int lo, int hi, int rt)
{
if (L <= lo && hi <= H)
{
return maxPoint[rt];
}
int mi = (lo + hi) >> 1;
int res = 0;
if (L <= mi)
res = max(res, query(L, H, lson));
if (mi < H)
res = max(res, query(L, H, rson));
return res;
}

int main()
{
#ifdef LOCAL
freopen("in.txt", "r", stdin);
#endif // LOCAL
int n, m;
while (~scanf("%d%d", &n, &m))
{
build(1, n, 1);
while (m--)
{
char op[2];
int a, b;
scanf("%s%d%d", op, &a, &b);
if (op[0] == 'Q')
printf("%d\n", query(a, b, 1, n, 1));
else
update(a, b, 1, n, 1);
}
}
return 0;
}