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HDU 1051 Wooden Sticks 貪心||DP

scanf rep code 子列 iss miss minimum span mission

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 22000 Accepted Submission(s): 8851


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 2 1 3

Source Asia 2001, Taejon (South Korea) 思路:將木棒按l,w 遞減的順序排列,統計關於遞減的連續子列的個數即為答案。 代碼:
 1 #include "cstdio"
 2
#include "iostream" 3 #include "algorithm" 4 #include "string" 5 #include "cstring" 6 #include "queue" 7 #include "cmath" 8 #include "vector" 9 #include "map" 10 #include "stdlib.h" 11 #include "set" 12 #define mj 13 #define db double 14 #define ll long long 15 using namespace std; 16 const int N=1e6+5; 17 const int mod=1e9+7; 18 const ll inf=1e16+10; 19 bool u[N]; 20 typedef struct stu{ 21 int l,w; 22 }M; 23 M s[5005]; 24 int cmp(M a,M b) 25 { 26 if(a.l==b.l) return a.w>=b.w; 27 return a.l>=b.l; 28 } 29 int main() 30 { 31 int t,n,i,j,ans; 32 scanf("%d",&t); 33 while(t--) 34 { 35 scanf("%d",&n); 36 for(i=0;i<n;i++) 37 scanf("%d%d",&s[i].l,&s[i].w),u[i]=0; 38 sort(s,s+n,cmp); 39 int mi; 40 ans=0; 41 for(i=0;i<n;i++) 42 { 43 if(u[i]) continue; 44 mi=s[i].w; 45 for(j=i+1;j<n;j++) 46 { 47 if(!u[j]&&s[j].w<=mi){ 48 mi=s[j].w; 49 u[j]=1; 50 } 51 } 52 ans++; 53 } 54 printf("%d\n",ans); 55 } 56 return 0; 57 }

HDU 1051 Wooden Sticks 貪心||DP