1.题目链接。题意就是给你一个序列,完后Q组询问 ,每次询问(l,r)区间内最大值和最小值之差。RMQ其实可以很简单的解决,不过最近在复习线段树,就用线段树写一下。
#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
using namespace std;
const int N = 1e5 + 10;
const int INF = 1e9;
int a[N];
#pragma warning(disable:4996)
int ans_x, ans_y;
struct node
{
int l, r;
int minn, mmax;
}s[N<<2];
void build(int l, int r, int n)
{
s[n].l = l;
s[n].r = r;
s[n].minn = INF;
s[n].mmax = 0;
if (l == r)
{
s[n].mmax = s[n].minn = a[l];
return;
}
int mid = (l + r) >> 1;
build(l, mid, n << 1);
build(mid + 1, r, n << 1 | 1);
s[n].mmax = max(s[n << 1].mmax, s[n << 1 | 1].mmax);
s[n].minn = min(s[n << 1].minn, s[n << 1 | 1].minn);
}
void query(int l, int r, int n)
{
if (s[n].l == l && s[n].r == r)
{
ans_x = max(ans_x, s[n].mmax);
ans_y = min(ans_y, s[n].minn);
return;
}
int mid = (s[n].l + s[n].r) >> 1;
if (r <= mid)
query(l, r, n << 1);
else if (l > mid)
query(l, r, n << 1 | 1);
else
{
query(l, mid, n <<1);
query(mid + 1, r, n<<1 | 1);
}
}
int main()
{
int m, q;
while (~scanf("%d%d", &m, &q))
{
for (int i = 1; i <= m; i++)
scanf("%d", &a[i]);
build(1, m, 1);
while (q--)
{
int x, y;
scanf("%d%d", &x, &y);
ans_x = 0;
ans_y = INF;
query(x, y, 1);
cout << ans_x-ans_y << endl;
}
}
}