HDOJ1677(铺砖问题)

Nested Dolls

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3512    Accepted Submission(s): 1059

Problem Description

Dilworth is the world’s most prominent collector of Russian nested dolls: he literally has thousands of them! You know, the wooden hollow dolls of different sizes of which the smallest doll is contained in the second smallest, and this doll is in turn contained in the next one and so forth. One day he wonders if there is another way of nesting them so he will end up with fewer nested dolls? After all, that would make his collection even more magnificent! He unpacks each nested doll and measures the width and height of each contained doll. A doll with width w1 and height h1 will fit in another doll of width w2 and height h2 if and only if w1 < w2 and h1 < h2. Can you help him calculate the smallest number of nested dolls possible to assemble from his massive list of measurements?

 

Input

On the first line of input is a single positive integer 1 <= t <= 20 specifying the number of test cases to follow. Each test case begins with a positive integer 1 <= m <= 20000 on a line of itself telling the number of dolls in the test case. Next follow 2m positive integers w1, h1,w2, h2, . . . ,wm, hm, where wi is the width and hi is the height of doll number i. 1 <= wi, hi <= 10000 for all i.

 

Output

For each test case there should be one line of output containing the minimum number of nested dolls possible.

 

Sample Input

4

3

20 30 40 50 30 40

4

20 30 10 10 30 20 40 50

3

10 30 20 20 30 10

4

10 10 20 30 40 50 39 51

 

Sample Output

1

2

3

2

思路：铺砖问题，宽度不等则按宽度有小到大排序，宽度相等则按高度由大到小排序。如果高度增加就往上摞，否则另起一堆。

#include <cstdio>
#include <algorithm>
using namespace std;
const int MAXN=20005;
struct Node{
    int w,h;
}doll[MAXN];
int n;
int dp[MAXN];
bool comp(Node no1,Node no2)
{
    if(no1.w!=no2.w)
    {
        return no1.w < no2.w;
    }
    else
    {
        return no1.h > no2.h;
    }
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&doll[i].w,&doll[i].h);
        }        
        sort(doll,doll+n,comp);
        dp[0]=doll[0].h;
        int k=1;
        for(int i=1;i<n;i++)
        {
            int j;
            for(j=0;j<k;j++)
            {
                if(dp[j]<doll[i].h)
                {
                    dp[j]=doll[i].h;
                    break;
                }
            }
            if(j==k)
                dp[k++]=doll[i].h;
        }
        printf("%d
",k);
    }
    return 0;
}