#include<bits/stdc++.h>
using namespace std;
#define INF INT_MAX
struct node
{
int maxx,minn;
int left,right;
};
node tree[1000001];
int num[50005];
void build(int id,int start,int end)
{
tree[id].left=start;
tree[id].right=end;
if(start==end)
{
tree[id].maxx=num[start];
tree[id].minn=num[start];
}
else
{
int mid=(start+end)/2;
build(id*2+1,start,mid);
build(id*2+2,mid+1,end);
tree[id].maxx=max(tree[2*id+1].maxx,tree[2*id+2].maxx);
tree[id].minn=min(tree[2*id+1].minn,tree[2*id+2].minn);
}
}
int query_max(int id,int l,int r)
{
int left=tree[id].left;
int right=tree[id].right;
if(left>r||right<l)
return 0;
l=max(left,l);
r=min(right,r);
if(l==left&&r==right)
return tree[id].maxx;
return max(query_max(2*id+1,l,r),query_max(2*id+2,l,r));
}
int query_min(int id, int l, int r)
{
int left = tree[id].left;
int right = tree[id].right;
if (left > r || right < l)
return INF; // 这个地方必须是一个较大的值
l = max(left, l);
r = min(right, r);
if (l == left && r == right)
return tree[id].minn;
return min(query_min(2 * id + 1, l, r), query_min(2 * id + 2, l, r));
}
int main()
{
ios::sync_with_stdio(false);
int l, r, n, m;
cin >> n >> m;
for (int i = 0; i < n; i++)
cin >> num[i];
build(0, 0, n - 1);
for (int i = 0; i < m; i++)
{
cin >> l >> r;
int ans = query_max(0, l - 1, r - 1) - query_min(0, l - 1, r - 1);
cout << ans << endl;
}
return 0;
}
效率至上(线段树)
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转载自blog.csdn.net/weixin_43797452/article/details/104805312
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