About Algorithm - Revision history

Fukakai: /* Counting Bits - (LeetCode) - ans[i] = ans[i >> 1] + (i & 1); */

2025-10-10T03:43:38Z

Counting Bits - (LeetCode) - ans[i] = ans[i >> 1] + (i & 1);

← Older revision		Revision as of 05:43, 10 October 2025
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	}		}
	}		}
	</pre>'''Two-Pointer Approach''' - ([https://leetcode.com/problems/container-with-most-water/ LeetCode]) - Calculate the area and move pointers<pre class="code java">		</pre>'''Two-Pointer Approach''' - ([https://leetcode.com/problems/container-with-most-water/ LeetCode]) - Calculate the area and move pointers

			* Calculate the area
			* Move pointers
			<pre class="code java">
	class Solution {		class Solution {
	public int maxArea(int[] height) {		public int maxArea(int[] height) {
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	</pre>		</pre>

	=== ~~'''~~Number of 1 bits~~'''~~ - [https://leetcode.com/problems/number-of-1-bits/ (LeetCode)] - '''if ((n & mask) != 0)''' ===		=== Number of 1 bits - [https://leetcode.com/problems/number-of-1-bits/ (LeetCode)] - '''if ((n & mask) != 0)''' ===

	* The equivalent of a pointer in an array is here a Mask, we move it using <<= 1 to the next bit		* The equivalent of a pointer in an array is here a Mask, we move it using <<= 1 to the next bit
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	</pre>		</pre>

	=== ~~'''~~Counting Bits~~'''~~ - ([https://leetcode.com/problems/counting-bits/description/ LeetCode]) - '''ans[i] = ans[i >> 1] + (i & 1);''' ===		=== Counting Bits - ([https://leetcode.com/problems/counting-bits/description/ LeetCode]) - '''ans[i] = ans[i >> 1] + (i & 1);''' ===
	<pre class="code java">		<pre class="code java">
	class Solution {		class Solution {
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	return ans;		return ans;
	}		}
			}
			</pre>

			=== Bit Manipulation - [https://leetcode.com/problems/missing-number/ Missing Number] - '''xorNums ^= nums[i] ^ i;''' ===
			<pre class="code java">
			class Solution {
			public int missingNumber(int[] nums) {
			int xorNums = nums.length;

			for(int i=0; i < nums.length; i++){
			xorNums ^= nums[i] ^ i;
			}
			return xorNums;
			}
			// public int missingNumber(int[] nums) {
			// Arrays.sort(nums);
			// for(int i=0; i < nums.length; i++){
			// if(i!=nums[i]) return i;
			// }
			// return nums.length;
			// }
	}		}
	</pre>		</pre>

Fukakai: /* Number of 1 bits - (LeetCode) - if ((n & mask) != 0) */

2025-10-07T03:36:09Z

Number of 1 bits - (LeetCode) - if ((n & mask) != 0)

@@ Line 197: / Line 197: @@
+}
 </pre>
 * [[QuickSort (Java)]]
 * [[Index.php?title=Bit Manipulation|Bit Manipulation]]

Fukakai: /* Number of 1 bits - (LeetCode) - */

2025-10-07T02:39:40Z

Number of 1 bits - (LeetCode) -

← Older revision		Revision as of 04:39, 7 October 2025
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	== Binary ==		== Binary ==

	=== Sum of Two Integers - ([https://leetcode.com/problems/sum-of-two-integers/ LeetCode]) ===		=== Sum of Two Integers - ([https://leetcode.com/problems/sum-of-two-integers/ LeetCode]) - '''int carry = (a & b) << 1;''' ===

	* Store the carry		* Store the carry
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	</pre>		</pre>

	=== '''Number of 1 bits''' - [https://leetcode.com/problems/number-of-1-bits/ (LeetCode)] - ===		=== '''Number of 1 bits''' - [https://leetcode.com/problems/number-of-1-bits/ (LeetCode)] - '''if ((n & mask) != 0)''' ===

	* The equivalent of a pointer in an array is here a Mask, we move it using <<= 1 to the next bit		* The equivalent of a pointer in an array is here a Mask, we move it using <<= 1 to the next bit

Fukakai: /* Number of 1 bits - (LeetCode) - */

2025-10-07T02:14:26Z

Number of 1 bits - (LeetCode) -

← Older revision		Revision as of 04:14, 7 October 2025
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	* The equivalent of a pointer in an array is here a Mask, we move it using <<= 1 to the next bit		* The equivalent of a pointer in an array is here a Mask, we move it using <<= 1 to the next bit
	* And continue to 32 bits as it is mentioned in the exercise.		* And continue to 32 bits as it is mentioned in the exercise.
			* & is a binary AND
	<pre class="code java">		<pre class="code java">
	class Solution {		class Solution {

Fukakai: /* Sum of Two Integers - (LeetCode) */

2025-10-07T00:18:00Z

Sum of Two Integers - (LeetCode)

@@ Line 174: / Line 174: @@
 </pre>
-=== Rest ===
+=== '''Number of 1 bits''' - [https://leetcode.com/problems/number-of-1-bits/ (LeetCode)] - ===
 * [[QuickSort (Java)]]
 * [[Index.php?title=Bit Manipulation|Bit Manipulation]]

Fukakai: /* Kadane’s Algorithm - adapted on cumulated products */

2025-10-06T23:53:00Z

Kadane’s Algorithm - adapted on cumulated products

@@ Line 156: / Line 156: @@
 == Binary ==
-=== Sum of Two Integers ===
+=== Sum of Two Integers - ([https://leetcode.com/problems/sum-of-two-integers/ LeetCode]) ===
 === Rest ===

Fukakai: /* Binary */

2025-10-06T23:49:34Z

Binary

← Older revision		Revision as of 01:49, 7 October 2025
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	== Binary ==		== Binary ==

	=== ~~Binary~~ ===		=== Sum of Two Integers ===

	=== Rest ===		=== Rest ===

Fukakai: /* Tips */

2025-10-06T23:49:08Z

Tips

← Older revision		Revision as of 01:49, 7 October 2025
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	=Tips=		=Tips=
	* Use Set/Hashet for unique values [https://leetcode.com/problems/contains-duplicate/description/ https://leetcode.com/problems/contains-duplicate/]		* Use '''Set/Hashet for unique values''' [https://leetcode.com/problems/contains-duplicate/description/ https://leetcode.com/problems/contains-duplicate/]
	* Use Math.max(int,int) to get the max number between a number and a calculation. https://leetcode.com/problems/best-time-to-buy-and-sell-stock/		* Use '''Math.max(int,int)''' to get the max number between a number and a calculation. https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
	* A product invert the sign, the max becomes the min, and the min becomes the max: https://leetcode.com/problems/maximum-product-subarray/		* A product invert the sign, the max becomes the min, and the min becomes the max: https://leetcode.com/problems/maximum-product-subarray/
	=Array ~~Algoritms~~=		* '''(a & b) << 1''' - is to carry
			=Array=

	==== '''Kadane’s Algorithm''' - adapted on cumulated products ====		==== '''Kadane’s Algorithm''' - adapted on cumulated products ====
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	</pre>		</pre>

	==== ~~[[Index.php?title~~=~~MergeSort\|MergeSort]]~~ ====		== Binary ==

			=== Binary ===

			=== Rest ===
	* [[QuickSort (Java)]]		* [[QuickSort (Java)]]
	* [[Index.php?title=Bit Manipulation\|Bit Manipulation]]		* [[Index.php?title=Bit Manipulation\|Bit Manipulation]]

Fukakai: /* 3 Sum - (LeetCode) - fix a value, use left and right pointers */

2025-10-06T04:00:18Z

3 Sum - (LeetCode) - fix a value, use left and right pointers

@@ Line 126: / Line 126: @@
+         }
          return new ArrayList<>(results);
+     }
+}

Fukakai: /* 3 Sum - (LeetCode) - fix a value, use left and right pointers */

2025-10-06T03:53:19Z

3 Sum - (LeetCode) - fix a value, use left and right pointers

← Older revision		Revision as of 05:53, 6 October 2025
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	</pre>		</pre>

	==== 3 Sum - ([https://leetcode.com/problems/3sum/ LeetCode]) - fix a value, use left and right pointers ====		==== '''3 Sum''' - ([https://leetcode.com/problems/3sum/ LeetCode]) - fix a value, use left and right pointers ====

	* Sort the array first !		* Sort the array first !