课程练习一 Problem I id： 1008

*题目编号  Problem I    id： 1008

*简单题意    

       木头被机器加工，如果后面的木头与前面的木头相比，重量大于等于前面的且长度大于等于前面的，则机器不用启动时间，否则则需要时间启动，求最短的启动时间

*解题思路  

先排序---然后选择第一个没有用过的木头，依次向后找，用掉所有可以用掉的木头，然后返回第一个没用过的木头继续找

*感想

这题竟然有重题。。。太巧了。

*AC源码

  # include <stdio.h>
  # include <algorithm> 
  struct st {
      int l, w, vis;
      bool operator<(const st&c)const {
          return l==c.l?w<c.w:l<c.l;
      }
  }stick[5001];
 
 int n;
 void read() {
     scanf("%d", &n);
     for(int i=0; i<n; i++) {
         scanf("%d%d", &stick[i].l, &stick[i].w);
         stick[i].vis = 0;
     }
 }
 
 void find(int i) {
     int k = i;
     for(int j=i+1; j<n; j++)
         if(!stick[j].vis)
             if(stick[k].w<=stick[j].w) {
                 stick[j].vis = 1;
                 k=j;
             }
 }
 
 void work() {
     int res = 0;
     std::sort(stick, stick+n);
     for(int i=0; i<n; i++) {
         if(!stick[i].vis) {
             stick[i].vis = 1;
             ++res;
             find(i);
         }
     }
     printf("%d\n", res);
 }
 
 int main() {
     int T, n;
     scanf("%d", &T);
     while(T--) {
         read();
         work();
     }
     return 0;
 }

Problem I

Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 20000/10000K (Java/Other)

Total Submission(s) : 80   Accepted Submission(s) : 42

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 ( 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

213

 

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