Sync LeetCode submission Runtime - 96 ms (28.04%), Memory - 307.4 MB (10.55%)

Author: koralkulacoglu

LeetCode/4187-best-reachable-tower/README.md

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+<p>You are given a 2D integer array <code>towers</code>, where <code>towers[i] = [x<sub>i</sub>, y<sub>i</sub>, q<sub>i</sub>]</code> represents the coordinates <code>(x<sub>i</sub>, y<sub>i</sub>)</code> and quality factor <code>q<sub>i</sub></code> of the <code>i<sup>th</sup></code> tower.</p>
+
+<p>You are also given an integer array <code>center = [cx, cy​​​​​​​]</code> representing your location, and an integer <code>radius</code>.</p>
+
+<p>A tower is <strong>reachable</strong> if its <strong>Manhattan distance</strong> from <code>center</code> is <strong>less than or equal</strong> to <code>radius</code>.</p>
+
+<p>Among all reachable towers:</p>
+
+<ul>
+	<li>Return the coordinates of the tower with the <strong>maximum</strong> quality factor.</li>
+	<li>If there is a tie, return the tower with the <strong>lexicographically smallest</strong> coordinate. If no tower is reachable, return <code>[-1, -1]</code>.</li>
+</ul>
+The <strong>Manhattan Distance</strong> between two cells <code>(x<sub>i</sub>, y<sub>i</sub>)</code> and <code>(x<sub>j</sub>, y<sub>j</sub>)</code> is <code>|x<sub>i</sub> - x<sub>j</sub>| + |y<sub>i</sub> - y<sub>j</sub>|</code>.
+
+<p>A coordinate <code>[x<sub>i</sub>, y<sub>i</sub>]</code> is <strong>lexicographically smaller</strong> than <code>[x<sub>j</sub>, y<sub>j</sub>]</code> if <code>x<sub>i</sub> &lt; x<sub>j</sub></code>, or <code>x<sub>i</sub> == x<sub>j</sub></code> and <code>y<sub>i</sub> &lt; y<sub>j</sub></code>.</p>
+
+<p><code>|x|</code> denotes the <strong>absolute</strong> <strong>value</strong> of <code>x</code>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">towers = [[1,2,5], [2,1,7], [3,1,9]], center = [1,1], radius = 2</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[3,1]</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<ul>
+	<li>Tower <code>[1, 2, 5]</code>: Manhattan distance = <code>|1 - 1| + |2 - 1| = 1</code>, reachable.</li>
+	<li>Tower <code>[2, 1, 7]</code>: Manhattan distance = <code>|2 - 1| + |1 - 1| = 1</code>, reachable.</li>
+	<li>Tower <code>[3, 1, 9]</code>: Manhattan distance = <code>|3 - 1| + |1 - 1| = 2</code>, reachable.</li>
+</ul>
+
+<p>All towers are reachable. The maximum quality factor is 9, which corresponds to tower <code>[3, 1]</code>.</p>
+</div>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">towers = [[1,3,4], [2,2,4], [4,4,7]], center = [0,0], radius = 5</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[1,3]</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<ul>
+	<li>Tower <code>[1, 3, 4]</code>: Manhattan distance = <code>|1 - 0| + |3 - 0| = 4</code>, reachable.</li>
+	<li>Tower <code>[2, 2, 4]</code>: Manhattan distance = <code>|2 - 0| + |2 - 0| = 4</code>, reachable.</li>
+	<li>Tower <code>[4, 4, 7]</code>: Manhattan distance = <code>|4 - 0| + |4 - 0| = 8</code>, not reachable.</li>
+</ul>
+
+<p>Among the reachable towers, the maximum quality factor is 4. Both <code>[1, 3]</code> and <code>[2, 2]</code> have the same quality, so the lexicographically smaller coordinate is <code>[1, 3]</code>.</p>
+</div>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">towers = [[5,6,8], [0,3,5]], center = [1,2], radius = 1</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">[-1,-1]</span></p>
+
+<p><strong>Explanation:</strong></p>
+
+<ul>
+	<li>Tower <code>[5, 6, 8]</code>: Manhattan distance = <code>|5 - 1| + |6 - 2| = 8</code>, not reachable.</li>
+	<li>Tower <code>[0, 3, 5]</code>: Manhattan distance = <code>|0 - 1| + |3 - 2| = 2</code>, not reachable.</li>
+</ul>
+
+<p>No tower is reachable within the given radius, so <code>[-1, -1]</code> is returned.</p>
+</div>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= towers.length &lt;= 10<sup>5</sup></code></li>
+	<li><code>towers[i] = [x<sub>i</sub>, y<sub>i</sub>, q<sub>i</sub>]</code></li>
+	<li><code>center = [cx, cy]</code></li>
+	<li><code>0 &lt;= x<sub>i</sub>, y<sub>i</sub>, q<sub>i</sub>, cx, cy &lt;= 10<sup>5</sup></code>​​​​​​​</li>
+	<li><code>0 &lt;= radius &lt;= 10<sup>5</sup></code></li>
+</ul>

LeetCode/4187-best-reachable-tower/solution.cpp

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+class Solution {
+public:
+    vector<int> bestTower(vector<vector<int>>& towers, vector<int>& center, int radius) {
+        auto dist = [&](int x, int y) {
+            int cx = center[0];
+            int cy = center[1];
+            return abs(cx - x) + abs(cy - y);
+        };
+        
+        vector<vector<int>> reach;
+        for (vector<int>& tower : towers) {
+            int x = tower[0];
+            int y = tower[1];
+            int q = tower[2];
+            if (dist(x, y) > radius) continue;
+            reach.push_back({x, y, q});
+        }
+
+        if (reach.empty()) return {-1, -1};
+
+        sort(reach.begin(), reach.end(), [](const vector<int>& a, const vector<int>& b) {
+            if (a[2] > b[2]) return true;
+            if (a[2] < b[2]) return false;
+            if (a[0] < b[0]) return true;
+            if (a[0] > b[0]) return false;
+            return a[1] < b[1];
+        });
+
+        return {reach[0][0], reach[0][1]};
+    }
+};