贪心--poj3069

Language: Default Saruman's Army Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 2668   Accepted: 1342 Description Saruman the White must lead his army along a straight path from Isengard to Helm’s Deep. To keep track of his forces, Saruman distributes seeing stones, known as palantirs, among the troops. Each palantir has a maximum effective range of R units, and must be carried by some troop in the army (i.e., palantirs are not allowed to “free float” in mid-air). Help Saruman take control of Middle Earth by determining the minimum number of palantirs needed for Saruman to ensure that each of his minions is within R units of some palantir. Input The input test file will contain multiple cases. Each test case begins with a single line containing an integer R, the maximum effective range of all palantirs (where 0 ≤ R ≤ 1000), and an integer n, the number of troops in Saruman’s army (where 1 ≤ n ≤ 1000). The next line contains n integers, indicating the positionsx1, …, xn of each troop (where 0 ≤ xi ≤ 1000). The end-of-file is marked by a test case with R = n = −1. Output For each test case, print a single integer indicating the minimum number of palantirs needed. Sample Input 0 3 10 20 20 10 7 70 30 1 7 15 20 50 -1 -1 Sample Output 2 4 下面是代码： #include #include using namespace std; int a[1010]; int main() { int R,N; while(cin>>R>>N) { if(R==-1&&N==-1) break; for(int i=0;i>a[i]; sort(a,a+N); int i=0,ans=0; while(i