hdu1051——Wooden Sticks

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 12086    Accepted Submission(s): 5011

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)

 

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类似于会场安排问题，点有5000个， 可以贪心解决，如果点少，其实可以建图，然后dfs染色去做，求出最少用的点数

#include <set>#include <map>#include <list>#include <stack>#include <queue>#include <vector>#include <cmath>#include <cstdlib>#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>using namespace std;const int N = 5010;struct node{    int l, w;}wood[N];bool mark[N];int cmp(node a, node b){    if (a.l != b.l)    {        return a.l < b.l;    }    return a.w < b.w;}int main(){    int t, n;    scanf("%d", &t);    while (t--)    {        scanf("%d", &n);        memset (mark, 0, sizeof(mark) );        for (int i = 0; i < n; ++i)        {            scanf("%d%d", &wood[i].l, &wood[i].w);        }        sort(wood, wood + n, cmp);        int ans = 0;        int mark_num = 0;        int p;        while (mark_num < n)        {            for (int i = 0; i < n; ++i)            {                if(mark[i] == 0)                {                    p = i;                    break;                }            }            ans++;            mark_num++;            mark[p] = 1;            for (int i = 0; i < n; ++i)            {                if (mark[i])                {                    continue;                }                if(wood[i].l >= wood[p].l && wood[i].w >= wood[p].w)                {                    mark[i] = 1;                    mark_num++;                    p = i;                }            }        }        printf("%d\n", ans);    }    return 0;}