hdoj.1051 Wooden Sticks【水题】 2015/04/22

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 13789    Accepted Submission(s): 5702

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

213

 

Source

Asia 2001, Taejon (South Korea) 

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>using namespace std;struct node{    int l;    int w;}p[5005];int t,n,i,j,ww,ans;bool vis[5005];bool cmp(node x,node y){    if( x.l != y.l )        return x.l<y.l;    else return x.w<y.w;}void solve(){    sort(p,p+n,cmp);    memset(vis,false,sizeof(vis));    ans = 0;    for( i = 0 ; i < n ; ++i )        if( !vis[i] ){            ans++;            vis[i] = true;            ww = p[i].w;            for( j = i +1 ; j < n ; ++j )                if( ( p[j].w >= ww ) && !vis[j] ){                    vis[j] = true;                    ww = p[j].w;                }        }    printf("%d\n",ans);}int main(){    scanf("%d",&t);    while(t--){        scanf("%d",&n);        for( i = 0 ; i < n ; ++i )            scanf("%d %d",&p[i].l,&p[i].w);        solve();    }    return 0;}

注：先排序，在比较，比较时要更新比较的木棍参数