POJ 1065-Wooden Sticks(贪心+暴力)

Time Limit: 1000MS Memory Limit: 10000KTotal Submissions: 18219 Accepted: 7622

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

题意：

投入第一根木棍需要 1m，若后面的木棍L2>=L1,W2>=W1,则不需要花费时间，否则需要。求最少花费的时间。

思路：

贪心+暴力。将木棍按照L从小到大，W从小到大的顺序排列。记录投进去的木棍，直到所有木棍都投进去为止。

CODE:

#include <iostream>#include <cstdio>#include <algorithm>#include <cmath>#include <cstring>#include <string>#include <stack>#include <queue>#include <vector>#include <set>#include <map>typedef long long ll;const int inf=0xffffff;using namespace std;const int M=5005;struct node{    int l,w;}nn[M];bool cmp_l(node a,node b){    if(a.l == b.l) return a.w <= b.w;    return a.l < b.l;}int main(){    //freopen("in.in","r",stdin);    int T;    scanf("%d",&T);    while(T--)    {        int n;        scanf("%d",&n);        for(int i=0;i<n;i++)            scanf("%d %d",&nn[i].l,&nn[i].w);        sort(nn,nn+n,cmp_l);        int res=0;        int t;        for(int i=0;i<n;i++)        {            if(nn[i].w == -1) continue;            else            {                res++;                t = nn[i].w;                nn[i].w = -1;                for(int j=i+1;j<n;j++)                {                    if(t <= nn[j].w && nn[j].w != -1)                    {                        t = nn[j].w;                        nn[j].w = -1;                    }                }            }        }        printf("%d\n",res);    }    return 0;}