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poj 2566 Bound Found(尺取法 好题)

时间:2015-08-28 07:05:38      阅读:146      评论:0      收藏:0      [点我收藏+]

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Description

Signals of most probably extra-terrestrial origin have been received and digitalized by The Aeronautic and Space Administration (that must be going through a defiant phase: "But I want to use feet, not meters!"). Each signal seems to come in two parts: a sequence of n integer values and a non-negative integer t. Well not go into details, but researchers found out that a signal encodes two integer values. These can be found as the lower and upper bound of a subrange of the sequence whose absolute value of its sum is closest to t. 
You are given the sequence of n integers and the non-negative target t. You are to find a non-empty range of the sequence (i.e. a continuous subsequence) and output its lower index l and its upper index u. The absolute value of the sum of the values of the sequence from the l-th to the u-th element (inclusive) must be at least as close to t as the absolute value of the sum of any other non-empty range.

 

Input

The input file contains several test cases. Each test case starts with two numbers n and k. Input is terminated by n=k=0. Otherwise, 1<=n<=100000 and there follow n integers with absolute values <=10000 which constitute the sequence. Then follow k queries for this sequence. Each query is a target t with 0<=t<=1000000000.

 

Output

For each query output 3 numbers on a line: some closest absolute sum and the lower and upper indices of some range where this absolute sum is achieved. Possible indices start with 1 and go up to n.

 

Sample Input

5 1
-10 -5 0 5 10
3
10 2
-9 8 -7 6 -5 4 -3 2 -1 0
5 11
15 2
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
15 100
0 0

 

Sample Output

 
5 4 4
5 2 8
9 1 1
15 1 15
15 1 15

 

Source

 
尺取法,注意 inf 初始化
 
技术分享
 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<set>
 6 #include<map>
 7 using namespace std;
 8 #define N 106006
 9 #define inf 1<<30
10 pair<int,int> g[N];
11 int main()
12 {
13     int n,k;
14     while(scanf("%d%d",&n,&k)==2)
15     {
16         if(n==0 && k==0) 
17           break;
18         int sum=0;
19         g[0]=make_pair(0,0);
20         for(int i=1;i<=n;i++){
21             int x;
22             scanf("%d",&x);
23             sum=sum+x;
24             g[i]=make_pair(sum,i);
25         }
26         sort(g,g+n+1);
27         while(k--){
28             
29             int val;
30             scanf("%d",&val);
31             
32             int minn=inf;
33             int ans,ansl=1,ansr=1;
34             int s=0,t=1;
35             for(;;){
36                 if(t>n)
37                   break;
38                    if(minn==0)
39                      break;
40                 int num=g[t].first-g[s].first;
41                 if(abs(num-val)<minn){
42                     minn=abs(num-val);
43                     ans=num;
44                     ansl=g[s].second;
45                     ansr=g[t].second;
46                 }
47                 
48                  if(num<val)
49                    t++;
50                 if(num>val)
51                   s++;
52                 if(s==t)
53                   t++;
54             }
55             if(ansl>ansr)  
56                 swap(ansl,ansr);  
57             printf("%d %d %d\n",ans,ansl+1,ansr); 
58         }
59         
60     }
61     return 0;
62 }
View Code

 

 

poj 2566 Bound Found(尺取法 好题)

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原文地址:http://www.cnblogs.com/UniqueColor/p/4765295.html

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