DEV Community

Ertugrul
Ertugrul

Posted on

🗓 Daily LeetCode Progress – Day 17

Problems Solved:

  • #3065 Minimum Operations to Exceed Threshold Value I
  • #283 Move Zeroes

This continues my daily series (Day 17: Count-Below-Threshold + In‑place Zero Push). Today I focused on two array problems: counting how many elements are below a threshold when we repeatedly remove the global minimum, and moving all zeros to the end while preserving order.

💡 What I Learned

  • For Minimum Operations to Exceed Threshold Value I, the operation “remove one occurrence of the smallest element” implies we must eliminate every value < k exactly once. Thus, after sorting, the answer is simply the count of values < k. (Sorting is optional; we can also count directly.)
  • For Move Zeroes, implementing it by erasing zeros in place and pushing them to the back preserves order but causes O(n²) behavior due to repeated middle erases on a vector/array. It still solves the problem correctly and demonstrates in‑place stability, but is not optimal versus the two‑pointer linear approach.
  • Both tasks highlight how problem constraints map to simple invariants: remove‑min step ⇒ all < k must go; stable in‑place reordering ⇒ zeros migrate without disturbing non‑zero relative order.

🧩 #3065 — Minimum Operations to Exceed Threshold Value I

C++ (Sort + Count Below k) 

class Solution {
public:
    int minOperations(vector<int>& nums, int k) {
        sort(nums.begin(), nums.end());
        int i = 0;
        while (i < nums.size() && nums[i] < k){
            i += 1;
        }
        return i;
    }
};
Enter fullscreen mode Exit fullscreen mode

Python (Sort + Count Below k) 

class Solution:
    def minOperations(self, nums: List[int], k: int) -> int:
        nums.sort()
        i = 0
        while i < len(nums) and nums[i] < k:
            i += 1
        return i
Enter fullscreen mode Exit fullscreen mode

Why it works: each operation always removes the current global minimum. As long as any element < k remains, that minimum is < k and must be removed once. Therefore, the minimal number of operations equals the number of elements < k.

Time: O(n log n) due to sort (a counting‑only variant can be O(n)).
Space: O(1) extra (in‑place sort).

🧩 #283 — Move Zeroes

C++ (In‑place erase + push_back) 

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
        int start= 0, end = nums.size()-1;
        while (start < end){
            if (nums[start] == 0){
                nums.push_back(nums[start]);
                nums.erase(nums.begin() + start);
                end--;
            }else{
                start++;
            }
        }
    }
};
Enter fullscreen mode Exit fullscreen mode

Python (In‑place pop/append) 

class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        start = 0
        end = len(nums)-1
        while start < end:
            if nums[start] == 0:
                nums.append(nums[start])
                nums.pop(start)
                end -= 1
            else:
                start += 1
Enter fullscreen mode Exit fullscreen mode

Why it works: whenever a zero is found, it is relocated to the end. Elements already processed keep their relative order, so stability is preserved.

Time: worst‑case O(n²) (due to middle erases/pops).
Space: O(1) extra.

Note: A two‑pointer O(n) alternative writes non‑zeros forward then fills trailing zeros. I kept the implementations above consistent with today’s code to reflect the approach I used.

📸 Achievements

  • Implemented threshold‑removal counting cleanly in both Python and C++.

treshold python

treshold cpp

  • Demonstrated an in‑place, stable zero‑mover using erase/pop mechanics.

zeroes python

zeroes cpp

📦 Complexity Recap

  • Minimum Operations to Exceed Threshold Value I: O(n log n) time (with sort), O(1) extra space.
  • Move Zeroes: O(n²) time with erase/pop, O(1) extra space. (Two‑pointer variant would be O(n).)

📣 Join the Journey

I’m solving and documenting problems daily in both Python and C++, covering arrays, linked lists, dynamic programming, and more. Follow along if you’re interested in systematic problem solving.

Links

Top comments (0)