Time: 94 ms (85.18%) | Memory: 67 MB (38.89%) - LeetSync

1762-furthest-building-you-can-reach/furthest-building-you-can-reach.js

@@ -0,0 +1,88 @@
+/**
+ * @param {number[]} heights
+ * @param {number} bricks
+ * @param {number} ladders
+ * @return {number}
+ */
+var furthestBuilding = function(h, b, l) {
+    const p = new MaxHeap();
+
+    let i = 0, diff = 0;
+    for (i = 0; i < h.length - 1; i++) {
+        diff = h[i + 1] - h[i];
+
+        if (diff <= 0) {
+            continue;
+        }
+
+        b -= diff;
+        p.push(diff);
+
+        if (b < 0) {
+            b += p.pop();
+            l--;
+        }
+
+        if (l < 0) {
+            break;
+        }
+    }
+
+    return i;
+};
+
+class MaxHeap {
+    constructor() {
+        this.heap = [];
+    }
+
+    push(val) {
+        this.heap.push(val);
+        this.heapifyUp();
+    }
+
+    pop() {
+        const max = this.heap[0];
+        const last = this.heap.pop();
+
+        if (this.heap.length > 0) {
+            this.heap[0] = last;
+            this.heapifyDown();
+        }
+
+        return max;
+    }
+
+    heapifyUp() {
+        let current = this.heap.length - 1;
+        while (current > 0) {
+            const parent = Math.floor((current - 1) / 2);
+            if (this.heap[parent] >= this.heap[current]) {
+                break;
+            }
+            [this.heap[parent], this.heap[current]] = [this.heap[current], this.heap[parent]];
+            current = parent;
+        }
+    }
+
+    heapifyDown() {
+        let current = 0;
+        while (true) {
+            let leftChild = 2 * current + 1;
+            let rightChild = 2 * current + 2;
+            let maxChild = leftChild;
+
+            if (rightChild < this.heap.length && this.heap[rightChild] > this.heap[leftChild]) {
+                maxChild = rightChild;
+            }
+
+            if (leftChild >= this.heap.length || this.heap[current] >= this.heap[maxChild]) {
+                break;
+            }
+
+            [this.heap[current], this.heap[maxChild]] = [this.heap[maxChild], this.heap[current]];
+            current = maxChild;
+        }
+    }
+}
+