Aug 16, 2025 · Jul 27, 2025 · Aug 8, 2025 · Aug 10, 2025 · Aug 15, 2025 · Aug 16, 2025
diff --git a/articles/arranging-coins.md b/articles/arranging-coins.md
 }
 ```

 ```csharp
 public class Solution {
    public int ArrangeCoins(int n) {
        int row = 0;
        while (n - row > 0) {
            row++;
            n -= row;
        }
        return row;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
 }
 ```

 ```csharp
 public class Solution {
    public int ArrangeCoins(int n) {
        int l = 1, r = n;
        int res = 0;

        while (l <= r) {
            int mid = l + (r - l) / 2;
            long coins = (long)mid * (mid + 1) / 2;

            if (coins > n) {
                r = mid - 1;
            } else {
                res = Math.Max(res, mid);
                l = mid + 1;
            }
        }

        return res;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
 }
 ```

 ```csharp
 public class Solution {
    public int ArrangeCoins(int n) {
        if (n <= 3) {
            return n == 1 ? 1 : n - 1;
        }

        int l = 1, r = (n / 2) + 1;
        while (l < r) {
            int mid = (l + r) / 2;
            long coins = (long)mid * (mid + 1) / 2;

            if (coins <= n) {
                l = mid + 1;
            } else {
                r = mid;
            }
        }

        return l - 1;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
 }
 ```

 ```csharp
 public class Solution {
    public int ArrangeCoins(int n) {
        int mask = 1 << 15;
        int rows = 0;

        while (mask > 0) {
            rows |= mask;
            long coins = (long)rows * (rows + 1) / 2;
            if (coins > n) {
                rows ^= mask;
            }
            mask >>= 1;
        }

        return rows;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
 }
 ```

 ```csharp
 public class Solution {
    public int ArrangeCoins(int n) {
        return (int)(Math.Sqrt(2L * n + 0.25) - 0.5);
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
diff --git a/articles/buy-two-chocolates.md b/articles/buy-two-chocolates.md

 ```javascript
 class Solution {
    /**
     * @param {number[]} prices
     * @param {number} money
     * @return {number}
     */
    buyChoco(prices, money) {
        let res = -1;
        for (let i = 0; i < prices.length; i++) {
 }
 ```

 ```csharp
 public class Solution {
    public int BuyChoco(int[] prices, int money) {
        int res = -1;
        for (int i = 0; i < prices.Length; i++) {
            for (int j = i + 1; j < prices.Length; j++) {
                if (prices[i] + prices[j] <= money) {
                    res = Math.Max(res, money - prices[i] - prices[j]);
                }
            }
        }
        return res == -1 ? money : res;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity

 ```javascript
 class Solution {
    /**
     * @param {number[]} prices
     * @param {number} money
     * @return {number}
     */
    buyChoco(prices, money) {
        prices.sort((a, b) => a - b);
        let buy = prices[0] + prices[1];
 }
 ```

 ```csharp
 public class Solution {
    public int BuyChoco(int[] prices, int money) {
        Array.Sort(prices);
        int buy = prices[0] + prices[1];
        return buy > money ? money : money - buy;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity

 ```javascript
 class Solution {
    /**
     * @param {number[]} prices
     * @param {number} money
     * @return {number}
     */
    buyChoco(prices, money) {
        let min1 = Infinity, min2 = Infinity;

 }
 ```

 ```csharp
 public class Solution {
    public int BuyChoco(int[] prices, int money) {
        int min1 = int.MaxValue, min2 = int.MaxValue;

        foreach (int p in prices) {
            if (p < min1) {
                min2 = min1;
                min1 = p;
            } else if (p < min2) {
                min2 = p;
            }
        }

        int leftover = money - min1 - min2;
        return leftover >= 0 ? leftover : money;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
diff --git a/articles/count-odd-numbers-in-an-interval-range.md b/articles/count-odd-numbers-in-an-interval-range.md
 }
 ```

 ```csharp
 public class Solution {
    public int CountOdds(int low, int high) {
        int odd = 0;
        for (int num = low; num <= high; num++) {
            if ((num & 1) == 1) {
                odd++;
            }
        }
        return odd;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
 }
 ```

 ```csharp
 public class Solution {
    public int CountOdds(int low, int high) {
        int length = high - low + 1;
        int count = length / 2;
        if ((length % 2 == 1) && (low % 2 == 1)) {
            count++;
        }
        return count;
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
 }
 ```

 ```csharp
 public class Solution {
    public int CountOdds(int low, int high) {
        return ((high + 1) >> 1) - (low >> 1);
    }
 }
 ```

 ::tabs-end

 ### Time & Space Complexity
Original file line number	Diff line number	Diff line change
Expand Up		@@ -56,6 +56,19 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int ArrangeCoins(int n) {
		int row = 0;
		while (n - row > 0) {
		row++;
		n -= row;
		}
		return row;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -155,6 +168,29 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int ArrangeCoins(int n) {
		int l = 1, r = n;
		int res = 0;

		while (l <= r) {
		int mid = l + (r - l) / 2;
		long coins = (long)mid * (mid + 1) / 2;

		if (coins > n) {
		r = mid - 1;
		} else {
		res = Math.Max(res, mid);
		l = mid + 1;
		}
		}

		return res;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -259,6 +295,30 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int ArrangeCoins(int n) {
		if (n <= 3) {
		return n == 1 ? 1 : n - 1;
		}

		int l = 1, r = (n / 2) + 1;
		while (l < r) {
		int mid = (l + r) / 2;
		long coins = (long)mid * (mid + 1) / 2;

		if (coins <= n) {
		l = mid + 1;
		} else {
		r = mid;
		}
		}

		return l - 1;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -345,6 +405,26 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int ArrangeCoins(int n) {
		int mask = 1 << 15;
		int rows = 0;

		while (mask > 0) {
		rows \|= mask;
		long coins = (long)rows * (rows + 1) / 2;
		if (coins > n) {
		rows ^= mask;
		}
		mask >>= 1;
		}

		return rows;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -393,6 +473,14 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int ArrangeCoins(int n) {
		return (int)(Math.Sqrt(2L * n + 0.25) - 0.5);
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -48,6 +48,11 @@ public:

		```javascript
		class Solution {
		/**
		* @param {number[]} prices
		* @param {number} money
		* @return {number}
		*/
		buyChoco(prices, money) {
		let res = -1;
		for (let i = 0; i < prices.length; i++) {
Expand All		@@ -62,6 +67,22 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int BuyChoco(int[] prices, int money) {
		int res = -1;
		for (int i = 0; i < prices.Length; i++) {
		for (int j = i + 1; j < prices.Length; j++) {
		if (prices[i] + prices[j] <= money) {
		res = Math.Max(res, money - prices[i] - prices[j]);
		}
		}
		}
		return res == -1 ? money : res;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -106,6 +127,11 @@ public:

		```javascript
		class Solution {
		/**
		* @param {number[]} prices
		* @param {number} money
		* @return {number}
		*/
		buyChoco(prices, money) {
		prices.sort((a, b) => a - b);
		let buy = prices[0] + prices[1];
Expand All		@@ -114,6 +140,16 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int BuyChoco(int[] prices, int money) {
		Array.Sort(prices);
		int buy = prices[0] + prices[1];
		return buy > money ? money : money - buy;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -185,6 +221,11 @@ public:

		```javascript
		class Solution {
		/**
		* @param {number[]} prices
		* @param {number} money
		* @return {number}
		*/
		buyChoco(prices, money) {
		let min1 = Infinity, min2 = Infinity;

Expand All		@@ -203,6 +244,26 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int BuyChoco(int[] prices, int money) {
		int min1 = int.MaxValue, min2 = int.MaxValue;

		foreach (int p in prices) {
		if (p < min1) {
		min2 = min1;
		min1 = p;
		} else if (p < min2) {
		min2 = p;
		}
		}

		int leftover = money - min1 - min2;
		return leftover >= 0 ? leftover : money;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -60,6 +60,20 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int CountOdds(int low, int high) {
		int odd = 0;
		for (int num = low; num <= high; num++) {
		if ((num & 1) == 1) {
		odd++;
		}
		}
		return odd;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -130,6 +144,19 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int CountOdds(int low, int high) {
		int length = high - low + 1;
		int count = length / 2;
		if ((length % 2 == 1) && (low % 2 == 1)) {
		count++;
		}
		return count;
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand DownExpand Up		@@ -179,6 +206,14 @@ class Solution {
		}
		```

		```csharp
		public class Solution {
		public int CountOdds(int low, int high) {
		return ((high + 1) >> 1) - (low >> 1);
		}
		}
		```

		::tabs-end

		### Time & Space Complexity
Expand Down