|
Problem Description
There is a pile of n wooden sticks. The length and weight of each stick are known in advance. The sticks are to be 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 are associated with cleaning operations and changing tools and shapes in the machine. The setup times of the woodworking machine are 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 will need no setup time for a stick of length l' and weight w' if l<=l' and w<=w'. Otherwise, it will need 1 minute for setup. You are 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 are (4,9), (5,2), (2,1), (3,5), and (1,4), then the minimum setup time should be 2 minutes since there is a sequence of pairs (1,4), (3,5), (4,9), (2,1), (5,2). |
|
Input
The input consists of T test cases. The number of test cases (T) is given in the first line of the input file. Each test case consists of two lines: The first line has an integer n , 1<=n<=5000, that represents the number of wooden sticks in the test case, and the second line contains n 2 positive integers l1, w1, l2, w2, ..., ln, wn, each of magnitude at most 10000 , where li and wi are the length and weight of the i th wooden stick, respectively. The 2n integers are delimited by one or more spaces.
|
|
Output
The 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
2 1 3 |
|
Source
Asia 2001, Taejon (South Korea)
|
【思路】
把wooden stick按length排序。
不断循环(很多个for，嵌套在while里面)，若下一个stick的length和weight都大于等于前一个处理的stick，那么删掉这个stick。
每一次循环开始时都增加1 min的 preprocess time.
#include<stdio.h>
#include"algorithm"
using namespace std;
struct stick{
int length;
int weight;
bool deleted = false;
};
int cmp(const stick &a, const stick &b)
{
return a.length < b.length;
}
int larger(const stick &a, const int l,const int w)
{
return a.length >= l&&a.weight >=w;
}
stick st[5000];
int main()
{
freopen("f://in.txt", "r", stdin);
freopen("f://out.txt", "w", stdout);
int testCase;
scanf("%d", &testCase);
while (testCase--)
{
memset(st, 0, sizeof(st));
int stickNum;
scanf("%d", &stickNum);
for (int i = 0; i < stickNum; i++)
scanf("%d%d", &st[i].length, &st[i].weight);
sort(st, st + stickNum, cmp);
int minTime = 0;
int leftAmount = stickNum;
while (leftAmount)
{
minTime++;
int lastLength = -1, lastWeight = -1;
for (int i = 0; i < stickNum ; i++)
if (st[i].deleted == false&&larger(st[i], lastLength, lastWeight))
{
st[i].deleted = true;
lastLength = st[i].length;
lastWeight = st[i].weight;
leftAmount--;
}
}
printf("%d\n", minTime);
}
return 0;
} 