feat: JS手写堆

Author: ceilf6

JS/algorithm/手写堆.js

@@ -0,0 +1,107 @@
+// https://www.nowcoder.com/practice/f5c52183dfb148489321f881239216c1
+// https://github.com/ceilf6/dataStructure/blob/main/learn2code/6-%E6%A0%91/%E4%BA%8C%E5%8F%89%E6%A0%91/%E5%A0%86/%E6%9C%80%E5%B0%8F%E5%A0%86.cpp
+
+// @datastructures-js/priority-queue
+
+const rl = require("readline").createInterface({ input: process.stdin });
+var iter = rl[Symbol.asyncIterator]();
+const readline = async () => (await iter.next()).value;
+
+void async function () {
+    const [n, m] = (await readline()).split(' ').map(it => Number(it))
+    const heap = (await readline()).split(' ').map(it => Number(it))
+    const ups = (await readline()).split(' ').map(it => Number(it))
+    function Down(i) {
+        while (true) { // 不断往下
+            const lIdx = 2 * i + 1
+            const rIdx = 2 * i + 2
+            let curSmall = heap[i]
+            const l = lIdx < n ? heap[lIdx] : null
+            const r = rIdx < n ? heap[rIdx] : null
+            let smallIdx
+            if (l !== null && l < curSmall) {
+                smallIdx = 2 * i + 1
+                curSmall = heap[smallIdx]
+            }
+            if (r !== null && r < curSmall) {
+                smallIdx = 2 * i + 2
+            }
+            if (!smallIdx) // 无需交换、无需再往下
+                break
+            [heap[i], heap[smallIdx]] = [heap[smallIdx], heap[i]]
+            if (smallIdx === lIdx)
+                i = lIdx
+            else if (smallIdx === rIdx)
+                i = rIdx
+        }
+    }
+    for (let i = Math.floor(n / 2) - 1; i >= 0; i--) {
+        Down(i) // 建堆
+    }
+    function Pop() {
+        const head = heap[0]
+        heap[0] = heap[heap.length - 1] // 出堆时将最后一个提到头然后往下调整
+        // heap.splice(heap.length-1,1)
+        heap.pop()
+        Down(0)
+        return head
+    }
+    function Up(i) {
+        while (true) { // 向上调整也需要不断往上
+            if (i <= 0)
+                break
+            const fatherIdx = Math.floor((i - 1) / 2)
+            const father = heap[fatherIdx]
+            if (father > heap[i]) {
+                [heap[i], heap[fatherIdx]] = [father, heap[i]]
+                i = fatherIdx
+            } else {
+                break // 没有交换就无需再往上调整
+            }
+        }
+    }
+    function Push(newVal) {
+        heap.push(newVal)
+        Up(heap.length - 1)
+    }
+    let maxNum = Math.max(...heap)
+    for (const up of ups) {
+        const head = Pop()
+        const newVal = head + up
+        if (newVal > maxNum) // 最大值只可能受新来的威胁
+            maxNum = newVal
+        Push(newVal)
+        // console.log(Math.max(...heap))
+        console.log(maxNum)
+    }
+}()
+
+/**
+ * 
+import heapq
+
+n, m = map(int, input().split())
+heap = list(map(int, input().split()))
+ups = list(map(int, input().split()))
+
+# 建堆（原地 O(n)）
+heapq.heapify(heap)
+
+# 维护当前最大值
+max_val = max(heap)
+
+for up in ups:
+    # 取最小值
+    smallest = heapq.heappop(heap)
+
+    new_val = smallest + up
+
+    # 放回堆
+    heapq.heappush(heap, new_val)
+
+    # 更新最大值
+    if new_val > max_val:
+        max_val = new_val
+
+    print(max_val)
+ */