題意：

給你n個木棍的長度和重量，讓其成為上升序列，如果不能達(dá)到，就需要重新一分鐘設(shè)置。
a）第一個木棍的準(zhǔn)備時間為1分鐘。
b）在處理長度為l和重量為w的棒之后，如果l <= l’并且w <= w’，則機(jī)器將不需要設(shè)置長度為l’和重量為w’的棒的設(shè)置時間。否則，將需要1分鐘進(jìn)行設(shè)置。

題目：

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

2
1
3

分析：

因為這道題有兩個變量需要我們考慮，所以先固定一個,使其先成為上升子序列后，然后只討論一個，類似很久之前的一道攔截導(dǎo)彈的題，找最長上升子序列，然后每次找到后狀態(tài)轉(zhuǎn)移到下一個。

AC代碼：

#include<stdio.h> #include<string.h> #include<algorithm> using namespace std; const int M=5e3+10; int t,n,ans; int book[M]; struct node{int a,b; }s[M]; bool cmp(node x,node y){if(x.b==y.b)return x.a<y.a;return x.b<y.b; } int main(){scanf("%d",&t);while(t--){ans=0;memset(book,0,sizeof(book));scanf("%d",&n);for(int i=0;i<n;i++)scanf("%d%d",&s[i].a,&s[i].b);sort(s,s+n,cmp);for(int i=0;i<n;i++){if(!book[i]){book[i]=1;for(int j=i+1;j<n;j++){if(s[i].a<=s[j].a&&!book[j]){s[i].a=s[j].a;book[j]=1;}}ans++;}}printf("%d\n",ans);}return 0; }

總結(jié)

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