定位查找一直不通过全部测试！！！
#include <iostream>
#include <vector>
using namespace std;
int main()
{
vector<int> a;
int n,m;
cin>>n;
int b;
for (int i = 0; i < n; ++i)
{
cin >> b;
a.push_back(b);
}
cin >> m;
for (int i = 0; i < n; ++i)
{
if (a[i] == m)
{
cout << i;
return 0;
}
}
cout << "No";
return 0;
}
#include <vector>
using namespace std;
int main()
{
vector<int> a;
int n,m;
cin>>n;
int b;
for (int i = 0; i < n; ++i)
{
cin >> b;
a.push_back(b);
}
cin >> m;
for (int i = 0; i < n; ++i)
{
if (a[i] == m)
{
cout << i;
return 0;
}
}
cout << "No";
return 0;
}