Balanced Lineup（线段树——根据区间找最值）

最新推荐文章于 2023-07-08 11:11:05 发布

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本文介绍了一种使用线段树解决寻找特定范围内最大值与最小值的问题，以帮助农民约翰在游戏中选择高度相近的奶牛组。通过构建线段树并进行区间查询，实现了高效求解指定区间内奶牛高度的最大值与最小值。

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Balanced Lineup

Time Limit: 5000ms

Memory Limit: 65536KB

64-bit integer IO format: %lld Java class name: Main

Submit Status PID: 3383

For the daily milking, Farmer John's N cows (1 ≤ N ≤ 50,000) always line up in the same order. One day Farmer John decides to organize a game of Ultimate Frisbee with some of the cows. To keep things simple, he will take a contiguous range of cows from the milking lineup to play the game. However, for all the cows to have fun they should not differ too much in height.

Farmer John has made a list of Q (1 ≤ Q ≤ 200,000) potential groups of cows and their heights (1 ≤ height ≤ 1,000,000). For each group, he wants your help to determine the difference in height between the shortest and the tallest cow in the group.

Input

Line 1: Two space-separated integers, N and Q.
Lines 2.. N+1: Line i+1 contains a single integer that is the height of cow i
Lines N+2.. N+ Q+1: Two integers A and B (1 ≤ A ≤ B ≤ N), representing the range of cows from A to B inclusive.

Output

Lines 1.. Q: Each line contains a single integer that is a response to a reply and indicates the difference in height between the tallest and shortest cow in the range.

Sample Input

Sample Output

6
3
0

query（）函数

#include <stdio.h>
#include <algorithm>
#define MAX 50000
using namespace std;
int a[MAX+10];
int low, hei;
struct node{
    int mx, mn;
}seg[MAX*4+10];

void build(int node, int l, int r)
{
    if(l == r){
        seg[node].mn = seg[node].mx = a[l];
        return;
    }
    int m = (l + r) / 2;
    build(node * 2, l, m);
    build(node * 2 + 1, m + 1, r);
    seg[node].mn = seg[node*2].mn < seg[node*2+1].mn ? seg[node*2].mn : seg[node*2+1].mn;
    seg[node].mx = seg[node*2].mx > seg[node*2+1].mx ? seg[node*2].mx : seg[node*2+1].mx;
}

void query (int node, int l, int r, int s, int e)
{
    if (l == s && r == e)
    {
        low = min (low, seg[node].mn);
        hei = max (hei, seg[node].mx);
        return ;
    }
    int m = (l + r) / 2;
    if (e <= m)
        query (2 * node, l, m, s, e);
    else if (s >= m + 1)
        query (2 * node + 1, m + 1, r, s, e);
    else
    {
        query(node * 2, l, m, s, m);
        query (2 * node + 1, m + 1, r, m + 1, e);
    }
}

int main()
{
    int n, m;
    scanf("%d %d", &n, &m);
    for(int i = 1; i <= n; i ++ ){
        scanf("%d", &a[i]);
    }
    build(1, 1, n);
    while(m -- ){
        int a, b;
        scanf("%d %d", &a, &b);
        low = 1000001;
        hei = 0;
        query(1, 1, n, a, b);
        printf("%d\n", hei - low);
    }
    return 0;
}