POJ 1065 Wooden Sticks

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Wooden Sticks

Time Limit:1000MS Memory Limit:10000KB 64bit IO Format:%I64d & %I64u

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 ( 9 , 4 ) , ( 2 , 5 ) , ( 1 , 2 ) , ( 5 , 3 ) , and ( 4 , 1 ) , then the minimum setup time should be 2 minutes since there is a sequence of pairs ( 4 , 1 ) , ( 5 , 3 ) , ( 9 , 4 ) , ( 1 , 2 ) , ( 2 , 5 ) .

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 2n 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

大致题意：C小加有一些木棒，它们的长度和质量都已经知道，需要一个机器处理这些木棒，机器开启的时候需要耗费一个单位的时间，如果第i+1个木棒的重量和长度都大于等于第i个处理的木棒，那么将不会耗费时间，否则需要消耗一个单位的时间。求最短的操作时间

分析：贪心，先按木棒长度由小到大排，长度相等时，按质量由小到大排序。然后对第i个木棒处理：选出单调递增子序列，并将单调递增子序列标记为-1（使用过）。选出后，时间+1.进行第i+1个木棒的处理

#include<stdio.h>#include<iostream>#include<algorithm>using namespace std;struct time{    int l,w;} a[5100];bool cmp(struct time c,struct time d){    if(c.l == d.l)        return c.w < d.w;    else        return c.l < d.l;}int main(){    int t,n;    scanf("%d",&t);    while(t--)    {        scanf("%d",&n);        for(int i = 0; i < n; i++)        {            scanf("%d %d",&a[i].l,&a[i].w);        }        sort(a,a + n,cmp);        int k = 0;        for(int i = 0; i < n; i++)        {            if(a[i].w != -1)            {                k++;                int wight = a[i].w;                for(int j = i; j < n; j++)                {                    if(a[j].w >= wight)                    {                        wight = a[j].w;                        a[j].w = -1;                    }                }            }        }        printf("%d\n",k);    }    return 0;}

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