LeetCode-34-在排序数组中查找元素的第一个和最后一个位置

LeetCode-34-在排序数组中查找元素的第一个和最后一个位置

#include<iostream>
using namespace std;
int main(){
int num[] = { 5, 7, 7, 8, 8, 8 };
int len = sizeof(num) / sizeof(num[0]);
int left = 0, right = len - 1;//有序数组通常用二分法查找
int mid = (left + right) / 2;
int s = -1, e = -1;
int target;
cin >> target;
while (left <= right){
if (num[mid] == target){
s = mid;
e = mid;
while (s - 1 >= 0 && num[s] == num[s - 1]){
s = s - 1;
}
while (e + 1 < len && num[e] == num[e + 1]){
e = e + 1;
}
break;
}
else if (num[mid] < target){
left = mid + 1;
}
else{
right = mid - 1;
}
mid = (left + right) / 2;
}
cout << "[" << s << "," << e << "]" << endl;
return 0;
}