1117 Eddington Number (25 分)
British astronomer Eddington liked to ride a bike. It is said that in order to show off his skill, he has even defined an "Eddington number", E -- that is, the maximum integer E such that it is for E days that one rides more than E miles. Eddington's own E was 87.
Now given everyday's distances that one rides for N days, you are supposed to find the corresponding E (≤N).
Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (≤105), the days of continuous riding. Then N non-negative integers are given in the next line, being the riding distances of everyday.
Output Specification:
For each case, print in a line the Eddington number for these N days.
Sample Input:
10
6 7 6 9 3 10 8 2 7 8
Sample Output:
6
题目大意:找出一个数e,满足该数字串中大于e的数大于等于e个。
解题思想:从大到小排序后,从最大的数开始遍历,e初始为0,判断e还能继续增加,只要判断此时v[i]是否大于e+1;这样做就满足了题意。如果换成暴力求解会有一个点超时。
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<vector>
using namespace std;
bool cmp(const int &a,const int &b){
return a>b;
}
int main(){
int n;
cin>>n;
vector<int> vec(n);
for(int i=0;i<n;i++)
scanf("%d",&vec[i]);
sort(vec.begin(),vec.end(),cmp);
int e = 0;
for(int i=0;i<n;i++){
if(vec[i] > e+1)
e++;
else
break;
}
cout<<e;
return 0;
}