心急的C小加（两种解法）

心急的C小加

时间限制：1000 ms  |  内存限制：65535 KB

难度：4

 

描述

C小加有一些木棒，它们的长度和质量都已经知道，需要一个机器处理这些木棒，机器开启的时候需要耗费一个单位的时间，如果第i+1个木棒的重量和长度都大 于等于第i个处理的木棒，那么将不会耗费时间，否则需要消耗一个单位的时间。因为急着去约会，C小加想在最短的时间内把木棒处理完，你能告诉他应该怎样做 吗？

输入

第一行是一个整数T(1<T<1500)，表示输入数据一共有T组。
每组测试数据的第一行是一个整数N（1<=N<=5000）,表示有N个木棒。接下来的一行分别输入N个木棒的L，W（0 < L ,W <= 10000），用一个空格隔开，分别表示木棒的长度和质量。

输出

处理这些木棒的最短时间。

样例输入

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 

样例输出

2
1
3


先贴下自己的dp超时代码：

#include<stdio.h>
#include<algorithm>
#define MAX(x,y) x>y?x:y
using namespace std;
struct Case{
    int L,W;
}strick[5001];
int cmp(Case a,Case b){
    if(a.L==b.L)return a.W<b.W;
    else return a.L<b.L;
}
int main(){
    int T,N,dp[5001],max;
    scanf("%d",&T);
    while(T--){
        scanf("%d",&N);
        for(int i=0;i<N;++i){dp[i]=1;
        scanf("%d%d",&strick[i].L,&strick[i].W);
        }
        sort(strick,strick+N,cmp);
        max=0;
        for(int i=0;i<N;++i){
            for(int j=0;j<=i;++j){
                if(strick[j].W>strick[i].W)dp[i]=dp[j]+1;
                max=MAX(dp[i],max);
            }
        }
        printf("%d
",max);
    }
    return 0;
}

借助大神理解解写的代码：

#include<stdio.h>

#include<algorithm>

using namespace std;

struct Case{

    int L,W,dis;

};

struct Case stick[5001];

int cmp(Case a,Case b){

    if(a.L==b.L)return a.W<b.W;

    else return a.L<b.L;

}

int main(){int T,N,t,flot;

scanf("%d",&T);

while(T--){

    scanf("%d",&N);

    for(int i=0;i<N;++i)scanf("%d%d",&stick[i].L,&stick[i].W),stick[i].dis=1;

    sort(stick,stick+N,cmp);flot=0;

    for(int i=0;i<N;++i){

        if(stick[i].dis==0)continue;

        t=stick[i].W;

        for(int j=i+1;j<N;++j){

            if(stick[j].dis&&t<=stick[j].W)stick[j].dis=0,t=stick[j].W;

        }

        flot++;

    }

    printf("%d
",flot);

}

    return 0;

}

/*题解：




结构体排序，一级排木棒的重量，二级排木棒的长度，均由小到大。




进行了多少次外层循环，就是花费的分钟数。




*/ 

若排序后，如图：

则，花费了2分钟。 

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 14880    Accepted Submission(s): 6105

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

 两题一样.....