HDOJ-----1051Wooden Sticks贪心

Wooden Sticks

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 18670    Accepted Submission(s): 7647

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

WA的太多，似乎有点不敢下手了

调整心态，相信自己

#include<cstdio>
#include<cstring>
#include<algorithm>
#define maxn 5010
#define ll long long
#define inf 0x3f3f3f3f
using namespace std;
bool vis[maxn];
int ans, n;
struct node{
    int l, w;
}dp[maxn];
bool cmp(node a, node b){
    if(a.l == b.l){
        return a.w < b.w;
    }
    return a.l < b.l;
}
int main(){
    int c, t;
    scanf("%d", &t);
    while(t--){
        scanf("%d", &n);
        memset(dp, 0, sizeof(dp));
        memset(vis, false, sizeof(vis));
        for(int i = 1; i <= n; i++){
            scanf("%d%d", &dp[i].l, &dp[i].w);
        }
        sort(dp+1, dp+n+1, cmp);
        ans = 0;
        for(int i = 1; i <= n; i++){
            if(vis[i]){
                continue;
            }
            c = dp[i].w;
            for(int j = i+1; j <= n; j++){
                if(!vis[j] && c <= dp[j].w){
                    c = dp[j].w;
                    vis[j] = true;
                }
            }
            ans++;
        }
        printf("%d\n", ans);
    }
    return 0;
}