题目描述
二分
C++ 代码
#include<iostream>
using namespace std;
const int N = 100010;
int nums[N];
int search_first(int k, int l, int r)
{
while(l < r)
{
int mid = l + r >> 1;
if (nums[mid] >= k) r = mid;
else l = mid + 1;
}
if (nums[l] == k) return l;
else return -1;
}
int search_second(int k, int l, int r)
{
while(l < r)
{
int mid = l + r + 1 >> 1;
if (nums[mid] <= k) l = mid;
else r = mid - 1;
}
if (nums[l] == k) return l;
else return -1;
}
int main()
{
int n, q;
scanf("%d%d", &n, &q);
for (int i = 0; i < n; i ++) scanf("%d", &nums[i]);
while (q --)
{
int k;
scanf("%d", &k);
int first = search_first(k, 0, n - 1);
int second = search_second(k, 0, n - 1);
printf("%d %d\n", first, second);
}
return 0;
}