#include<iostream> #include<string> #include <cstdlib> #include <algorithm> #include <cstdio> using namespace std; const int N = 1e5 + 5; struct node { int l,r; int maxn, minn; }tree[N*3]; int a[N]; void Build(int i, int l, int r) { tree[i].l = l; tree[i].r = r; if (l == r) { tree[i].maxn = a[l]; tree[i].minn = a[l]; return; } int mid = (l+r) >> 1; Build(i<<1, l, mid); Build(i<<1|1, mid +1, r); tree[i].maxn = max(tree[i<<1].maxn, tree[i<<1|1].maxn); tree[i].minn = min(tree[i<<1].minn, tree[i<<1|1].minn); } int Querymax(int i, int a, int b) { if (a == tree[i].l && b == tree[i].r) { return tree[i].maxn; } int mid = (tree[i].l + tree[i].r) >> 1; if (b <= mid) Querymax(i<<1, a, b); else if(a > mid) Querymax(i<<1|1, a, b); else { return max(Querymax(i<<1,a,mid), Querymax(i<<1|1, mid + 1, b)); } } int Querymin(int i, int a, int b) { if (a == tree[i].l && b == tree[i].r) { return tree[i].minn; } int mid = (tree[i].l + tree[i].r) >> 1; if (b <= mid) Querymin(i<<1, a, b); else if(a > mid) Querymin(i<<1|1, a, b); else { return min(Querymin(i<<1,a,mid), Querymin(i<<1|1, mid + 1, b)); } } int main() { int n, q; scanf("%d %d", &n, &q); for (int i = 1; i <= n; i++) { scanf("%d", &a[i]); } Build(1,1,n); for (int i = 0; i < q; i++) { int t1, t2; scanf("%d %d", &t1, &t2); printf("%d\n",Querymax(1,t1,t2)-Querymin(1,t1,t2)); } }
题目链接 http://poj.org/problem?id=3264