Merge pull request #2770 from suinming/kamacoder-127-js

feat: 127. 骑士的攻击增加js解法

Author: youngyangyang04

problems/kamacoder/0126.骑士的攻击astar.md

@@ -375,6 +375,131 @@ for _ in range(n):
 
 ### Javascript
 
+```js
+class MinHeap {
+  constructor() {
+    this.val = []
+  }
+  push(val) {
+    this.val.push(val)
+    if (this.val.length > 1) {
+      this.bubbleUp()
+    }
+  }
+  bubbleUp() {
+    let pi = this.val.length - 1
+    let pp = Math.floor((pi - 1) / 2)
+    while (pi > 0 && this.val[pp][0] > this.val[pi][0]) {
+      ;[this.val[pi], this.val[pp]] = [this.val[pp], this.val[pi]]
+      pi = pp
+      pp = Math.floor((pi - 1) / 2)
+    }
+  }
+  pop() {
+    if (this.val.length > 1) {
+        let pp = 0
+        let pi = this.val.length - 1
+        ;[this.val[pi], this.val[pp]] = [this.val[pp], this.val[pi]]
+        const min = this.val.pop()
+        if (this.val.length > 1) {
+          this.sinkDown(0)
+        }
+        return min        
+    } else if (this.val.length == 1) {
+        return this.val.pop()
+    }
+
+  }
+  sinkDown(parentIdx) {
+    let pp = parentIdx
+    let plc = pp * 2 + 1
+    let prc = pp * 2 + 2
+    let pt = pp // temp pointer
+    if (plc < this.val.length && this.val[pp][0] > this.val[plc][0]) {
+        pt = plc
+    }
+    if (prc < this.val.length && this.val[pt][0] > this.val[prc][0]) {
+        pt = prc
+    }
+    if (pt != pp) {
+        ;[this.val[pp], this.val[pt]] = [this.val[pt], this.val[pp]]
+        this.sinkDown(pt)
+    }
+  }
+}
+
+const moves = [
+    [1, 2], 
+    [2, 1], 
+    [-1, -2], 
+    [-2, -1],
+    [-1, 2], 
+    [-2, 1],
+    [1, -2], 
+    [2, -1]
+]
+
+function dist(a, b) {
+    return ((a[0] - b[0])**2 + (a[1] - b[1])**2)**0.5
+}
+
+function isValid(x, y) {
+    return x >= 1 && y >= 1 && x < 1001 && y < 1001
+}
+
+function bfs(start, end) {
+    const step = new Map()
+    step.set(start.join(" "), 0)
+    const q = new MinHeap()
+    q.push([dist(start, end), start[0], start[1]])
+    
+    while(q.val.length) {
+        const [d, x, y] = q.pop()
+        // if x and y correspond to end position output result
+        if (x == end[0] && y == end[1]) {
+            console.log(step.get(end.join(" ")))
+            break;
+        }
+        for (const [dx, dy] of moves) {
+            const nx = dx + x
+            const ny = dy + y
+            if (isValid(nx, ny)) {
+                const newStep = step.get([x, y].join(" ")) + 1
+                const newDist = dist([nx, ny], [...end])
+                const s = step.get([nx, ny].join(" ")) ? 
+                    step.get([nx, ny]) : 
+                    Number.MAX_VALUE
+                if (newStep < s) {
+                    q.push(
+                        [
+                            newStep + newDist, 
+                            nx, 
+                            ny
+                        ]
+                    )
+                    step.set([nx, ny].join(" "), newStep)
+                } 
+            }
+        }
+    }
+}
+
+async function main() {
+    const rl = require('readline').createInterface({ input: process.stdin })
+    const iter = rl[Symbol.asyncIterator]()
+    const readline = async () => (await iter.next()).value
+    const n = Number((await readline()))
+    
+    // find min step
+    for (let i = 0 ; i < n ; i++) {
+        const [s1, s2, t1, t2] = (await readline()).split(" ").map(Number)
+        bfs([s1, s2], [t1, t2])
+    }
+}
+
+main()
+```
+
 ### TypeScript
 
 ### PhP