Title: https://leetcode-cn.com/problems/search-insert-position/
Solution 1, Violent
O (n) O (1)
Pay attention to two conditions a. When there are no elements in the array b. The last element is not greater than the target
class Solution {
public:
int searchInsert(vector<int>& nums, int target) {
size_t i = 0;
while (i < nums.size()) {
if (nums[i] >= target) {
return i;
}
i++;
}
return i == nums.size() ? i : -1;
}
};
Solution 2, binary search
O (logn) O (1)
Note that the loop termination condition, the value of mid, and l + r may cross the boundary!
class Solution {
public:
int searchInsert(vector<int>& nums, int target) {
size_t l = 0, r = nums.size();
while (l < r) {
// size_t mid = (l + r) / 2;
size_t mid = l + (r - l) / 2;
if (nums[mid] == target) {
return mid;
}
if (nums[mid] < target) {
l = mid + 1;
}
if (nums[mid] > target) {
r = mid;
}
}
return l;
}
};
EOF
