POJ1065Wooden Sticks[DP LIS]
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Wooden Sticks
Time Limit: 1000MS | Memory Limit: 10000K | |
Total Submissions: 21902 | Accepted: 9353 |
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 ) .
(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
Source
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和poj3636同样的道理
因为偏序关系是<=,所以w从小到大相同l小的在前,找最长下降子序列
#include <iostream> #include <cstdio> #include <algorithm> #include <cstring> using namespace std; const int N=5005,INF=1e9; struct data{ int w,l; }da[N]; bool cmpda(data a,data b){ if(a.w>b.w) return 0; if(a.w<b.w) return 1; if(a.w==b.w) return a.l<b.l?1:0; return 1; } int t,n; int f[N],g[N],a[N]; bool cmp(int a,int b){ return a>b; } int dp(){ int ans=0; sort(da+1,da+1+n,cmpda); memset(f,0,sizeof(f)); for(int i=1;i<=n;i++) g[i]=-INF,a[i]=da[i].l; for(int i=1;i<=n;i++){ int k=lower_bound(g+1,g+1+n,a[i],cmp)-g; f[i]=k; g[k]=a[i]; ans=max(ans,f[i]); } return ans; } int main(int argc, const char * argv[]) { scanf("%d",&t); for(int i=1;i<=t;i++){ scanf("%d",&n); for(int i=1;i<=n;i++) scanf("%d%d",&da[i].l,&da[i].w); printf("%d\n",dp()); } return 0; }
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