Wooden SticksTime
limit:2000/1000 MS (java/others) Memory limit:65536/32768 K (java/others)
Total submission (s): 14161 Accepted Submission (s): 5860
Problem Descriptionthere is a pile of n wooden sticks. The length and weight of each stick is known in advance. The sticks is processed by a woodworking machine in one by one fashion. It needs some time, called setup time, for the machine to prepare processing a stick. The setup times is associated with cleaning operations and changing tools and shapes. The setup times of the woodworking machine is given as follows:
(a) The setup time for the first wooden stick is 1 minute.
(b) Right after processing a stick of length L and weight W, the machine would need no setup time for a stick of length l ' and weight W ' if l<=l ' and W<=w '. Otherwise, it'll need 1 minute for setup.
You is to find the minimum setup time to process a given pile of n wooden sticks. For example, if you have five sticks whose pairs of length and weight is (4,9), (5,2), (2,1), (3,5), and (1,4), then the Minimum setup time should be 2 minutes since there are a sequence of pairs (1,4), (3,5), (4,9), (2,1), (5,2).
Inputthe input consists of T test cases. The number of test cases (T) is given on the first line of the input file. Each test case consists of a lines:the first line has a integer n, 1<=n<=5000, that represents the number of Wo Oden sticks in the test case, and the second line contains n 2 positive integers L1, W1, L2, W2, ..., LN, WN, each of Magn Itude at most 10000, where Li and wi is the length and weight of the i th wooden stick, respectively. The 2n integers is delimited by one or more spaces.
Outputthe output should contain the minimum setup time in minutes, one per line.
Sample Input
3 5 4 9 5 2 2 1 3 5 1 4 3 2 2 1 1 2 2 3 1 3 2 2 3 1
Sample Output
213
Sourceasia 2001, Taejon (South Korea)
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Today is the Dragon Boat Festival, I wish everyone C Dragon Boat Festival Health! Good! Nonsense not to say, start our daily one water time! Finally came a not so water problem, first explain the main idea of the topic:
Title: give you the length and weight of the n stick. Find the shortest time to make the stick according to the requirements. It takes 1 minutes to build the first stick, and if the stick is longer and heavier than the stick, then the stick will not take time! Then if you continue to make it, the next stick will be longer and heavier than the previous one, and the stick will not take much time! And so on, on the other hand, it takes a minute, and then you can find out the minimum amount of time it takes to make this batch of sticks!
Problem-solving ideas: In fact, probably understand the test instructions, you can know, this question is greedy! Then the key is the choice of greedy strategy! The topic said to ask for the minimum time, it is certainly required length and weight are relatively minimum, my strategy is as follows:
1. First sort by the length of the stick, if the length is equal, weight is placed in front. 2.of courseafter sorting, not all of the next stick weight and length are greater than the previous one, but we can be based on the order of the array set up and then multiple scans, compared. 3. Compare their weights according to the established array, or ANS plus 1 if the tag array is greater than skip.
#include <cstdio> #include <iostream> #include <algorithm>using namespace std;const int maxn = 5010; struct stick{int length; int weight; bool Vis;}; BOOL CMP (stick S1,stick s2) {if (s1.length==s2.length) return s1.weight<s2.weight; else return s1.length<s2.length;} int N;stick S[maxn];int Main () {int t; scanf ("%d", &t); while (t--) {scanf ("%d", &n); for (int i=0;i<n;i++) {scanf ("%d%d", &s[i].length,&s[i].weight); S[i].vis = false; } sort (s,s+n,cmp); int ans = 0; for (int i=0;i<n;i++) {if (!s[i].vis) {s[i].vis=true; ++ans; int weight = S[i].weight; for (int j=i+1;j<n;j++) {if (!s[j].vis && s[j].weight>=weight) {S[j].vis = true; Weight = S[J].WEight }}}} printf ("%d\n", ans); } return 0;}
Hdu-1051-wooden Sticks (c + + && non-water greedy!) )
