杭电5443 The Water Problem

我就是我 2022-05-15 12:20 161阅读 0赞

题目链接:[这里写链接内容][Link 1]  
Problem Description  
In Land waterless, water is a very limited resource. People always fight for the biggest source of water. Given a sequence of water sources with a1,a2,a3,…,an representing the size of the water source. Given a set of queries each containing 2 integers l and r, please find out the biggest water source between al and ar.

Input  
First you are given an integer T(T≤10) indicating the number of test cases. For each test case, there is a number n(0≤n≤1000) on a line representing the number of water sources. n integers follow, respectively a1,a2,a3,…,an, and each integer is in \{1,…,106\}. On the next line, there is a number q(0≤q≤1000) representing the number of queries. After that, there will be q lines with two integers l and r(1≤l≤r≤n) indicating the range of which you should find out the biggest water source.

Output  
For each query, output an integer representing the size of the biggest water source.

Sample Input  
3  
1  
100  
1  
1 1  
5  
1 2 3 4 5  
5  
1 2  
1 3  
2 4  
3 4  
3 5  
3  
1 999999 1  
4  
1 1  
1 2  
2 3  
3 3

Sample Output  
100  
2  
3  
4  
4  
5  
1  
999999  
999999  
1

区间最值查询问题，直接上st。

#include<iostream>
    #include<cstdio>
    
    const int N=1008;
    int a[N],stmax[N][N],log[N];
    int n;
    using namespace std;
    
    void init() {
    	log[0]=-1;
    	for(int i=1; i<=1000; i++) {
    		log[i]=log[i/2]+1;
    
    	}
    	for(int i=1; i<=n; i++) {
    		stmax[0][i]=a[i];
    	}
    	for(int i=1; i<=log[n]; i++) {
    		for(int j=1; j+(1<<i)-1<=n; j++) {
    			stmax[i][j]=max(stmax[i-1][j],stmax[i-1][j+(1<<(i-1))]);
    		}
    	}
    
    }
    int rmq_max(int l,int r) {
    	int t=log[r-l+1];//2^log[len]>len/2;
    	return max(stmax[t][l],stmax[t][r-(1<<t)+1]);
    }
    int main() {
    	int t;
    	scanf("%d",&t);
    	while(t--) {
    	scanf("%d",&n);
    	for(int i=1; i<=n; i++) {
    		scanf("%d",&a[i]);
    	}
    	init();
    	int q;
    	scanf("%d",&q);
    	while(q--) {
    	int l,r;
    	scanf("%d%d",&l,&r);
    	printf("%d\n",rmq_max(l,r));
    		}
    	}
    
    
    }

[Link 1]: http://acm.hdu.edu.cn/showproblem.php?pid=5443