Apr 9, 2023 · Apr 10, 2023
diff --git a/Uncategorized/Two Pointers/README.md b/Uncategorized/Two Pointers/README.md
 # Two Pointers

 Two pointers algorithm is a very useful technique in solving many problems, especially those that require scanning through arrays or lists.

 One practical example of using the two pointers algorithm is in finding pairs of numbers in an array that add up to a given target value.

 But, I prefer to provide example from the [leetcode](https://leetcode.com/problems/container-with-most-water/).

 ![question_11.jpg](img%2Fquestion_11.jpg)

 ```
 You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).

 Find two lines that together with the x-axis form a container, such that the container contains the most water.

 Return the maximum amount of water a container can store.

 Notice that you may not slant the container.

 Input: height = [1,8,6,2,5,4,8,3,7]
 Output: 49
 Explanation: The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49.
 ```

 ## Complexity
 * **Time**: O(n)
 * **Space**: O(1)

 ## References:

 * [DSA: Two-pointers algorithm. Review with the step-by-step guide](https://medium.com/@alexeyskrobot/dsa-two-pointers-algorithm-review-with-the-step-by-step-guide-e8368e11a144)
diff --git a/Uncategorized/Two Pointers/code.js b/Uncategorized/Two Pointers/code.js
 const { Tracer, Array1DTracer, LogTracer, Layout, VerticalLayout } = require('algorithm-visualizer');

 const tracer = new Array1DTracer('Input array');
 const areaTracer = new Array1DTracer('Max area calculation');
 const logger = new LogTracer();

 Layout.setRoot(new VerticalLayout([tracer, areaTracer, logger]));

 function maxArea(height) {
    tracer.set(height)

    let left = 0;
    let right = height.length - 1;
    let maxArea = 0;

    while (left < right) {
        tracer.select(left);
        tracer.select(right);
        Tracer.delay();
        logger.println(`Checking area between ${left} and ${right}`);

        const h = Math.min(height[left], height[right]);
        areaTracer.patch(0, h)
        Tracer.delay();

        const w = right - left;
        areaTracer.patch(1, h)
        Tracer.delay();

        const area = h * w;
        maxArea = Math.max(maxArea, area);

        areaTracer.patch(2, maxArea)
        Tracer.delay();

        tracer.deselect(left, right)
        Tracer.delay();

        if (height[left] < height[right]) {
            left++;
        } else {
            right--;
        }
    }

    return maxArea;
 }

 const height1 = [1,8,6,2,5,4,8,3,7];
 console.log(maxArea(height1)); // Output: 49
diff --git a/Uncategorized/Two Pointers/img/question_11.jpg b/Uncategorized/Two Pointers/img/question_11.jpg
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,31 @@
		# Two Pointers

		Two pointers algorithm is a very useful technique in solving many problems, especially those that require scanning through arrays or lists.

		One practical example of using the two pointers algorithm is in finding pairs of numbers in an array that add up to a given target value.

		But, I prefer to provide example from the [leetcode](https://leetcode.com/problems/container-with-most-water/).

		![question_11.jpg](img%2Fquestion_11.jpg)

		```
		You are given an integer array height of length n. There are n vertical lines drawn such that the two endpoints of the ith line are (i, 0) and (i, height[i]).

		Find two lines that together with the x-axis form a container, such that the container contains the most water.

		Return the maximum amount of water a container can store.

		Notice that you may not slant the container.

		Input: height = [1,8,6,2,5,4,8,3,7]
		Output: 49
		Explanation: The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49.
		```

		## Complexity
		* Time: O(n)
		* Space: O(1)

		## References:

		* [DSA: Two-pointers algorithm. Review with the step-by-step guide](https://medium.com/@alexeyskrobot/dsa-two-pointers-algorithm-review-with-the-step-by-step-guide-e8368e11a144)
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,50 @@
		const { Tracer, Array1DTracer, LogTracer, Layout, VerticalLayout } = require('algorithm-visualizer');

		const tracer = new Array1DTracer('Input array');
		const areaTracer = new Array1DTracer('Max area calculation');
		const logger = new LogTracer();

		Layout.setRoot(new VerticalLayout([tracer, areaTracer, logger]));

		function maxArea(height) {
		tracer.set(height)

		let left = 0;
		let right = height.length - 1;
		let maxArea = 0;

		while (left < right) {
		tracer.select(left);
		tracer.select(right);
		Tracer.delay();
		logger.println(`Checking area between ${left} and ${right}`);

		const h = Math.min(height[left], height[right]);
		areaTracer.patch(0, h)
		Tracer.delay();

		const w = right - left;
		areaTracer.patch(1, h)
		Tracer.delay();

		const area = h * w;
		maxArea = Math.max(maxArea, area);

		areaTracer.patch(2, maxArea)
		Tracer.delay();

		tracer.deselect(left, right)
		Tracer.delay();

		if (height[left] < height[right]) {
		left++;
		} else {
		right--;
		}
		}

		return maxArea;
		}

		const height1 = [1,8,6,2,5,4,8,3,7];
		console.log(maxArea(height1)); // Output: 49