POJ 3264

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Balanced Lineup

Time Limit: 5000MS Memory Limit: 65536KTotal Submissions: 47359 Accepted: 22237Case Time Limit: 2000MS

Description

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

6 31734251 54 62 2

Sample Output

Source

USACO 2007 January Silver

一.题意分析

给出一组数据,并且给出多组左右端点,求出区间内的最大值与最小值之差

二.思路过程

RMQ问题,ST表

三.代码

#include <iostream>#include <cstdio>#include <cmath>using namespace std;int num[200001], MAXN[200001][20], MINN[200001][20];int n, q;void init(){int i, j;int k = log(double(n))/log(2.0);for (j = 1; j <= k; j++){for (i = 1; i <= n+1-(1<<j); i++){MAXN[i][j] = max(MAXN[i][j-1], MAXN[i+(1<<(j-1))][j-1]);MINN[i][j] = min(MINN[i][j-1], MINN[i+(1<<(j-1))][j-1]);}}}int main(){int i, a, b;scanf("%d%d", &n, &q);for (i = 1; i <= n; i++){scanf("%d", &num[i]);MAXN[i][0] = MINN[i][0] = num[i];}init();for (i = 1; i <= q; i++){scanf("%d%d", &a, &b);if (a > b) swap(a, b);int k = log(double(b-a+1))/log(2.0);int ans = max(MAXN[a][k], MAXN[b-(1<<k)+1][k]) - min(MINN[a][k], MINN[b-(1<<k)+1][k]);printf("%d\n", ans);}return 0;}/*6 31734251 54 62 2*/

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