feat: add js solution to lc problem: No.1395

Author: rain84

solution/1300-1399/1395.Count Number of Teams/README.md

@@ -579,6 +579,54 @@ function numTeams(rating: number[]): number {
 type Type = 'asc' | 'desc';
 ```
 
+#### JavaScript
+
+```js
+/**
+ * @param {number[]} rating
+ * @return {number}
+ */
+var numTeams = function (rating) {
+    const n = rating.length;
+    const f = {
+        asc: Array.from({ length: n }, () => Array(3).fill(-1)),
+        desc: Array.from({ length: n }, () => Array(3).fill(-1)),
+    };
+
+    const fn = (i, available, type) => {
+        if (!available) {
+            return 1;
+        }
+        if (f[type][i][available] !== -1) {
+            return f[type][i][available];
+        }
+
+        let ans = 0;
+        for (let j = i + 1; j < n; j++) {
+            if (rating[j] > rating[i]) {
+                if (type === 'asc') {
+                    ans += fn(j, available - 1, 'asc');
+                }
+            } else {
+                if (type === 'desc') {
+                    ans += fn(j, available - 1, 'desc');
+                }
+            }
+        }
+        f[type][i][available] = ans;
+
+        return ans;
+    };
+
+    let ans = 0;
+    for (let i = 0; i < n; i++) {
+        ans += fn(i, 2, 'asc') + fn(i, 2, 'desc');
+    }
+
+    return ans;
+};
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/1300-1399/1395.Count Number of Teams/README_EN.md

@@ -577,6 +577,54 @@ function numTeams(rating: number[]): number {
 type Type = 'asc' | 'desc';
 ```
 
+#### JavaScript
+
+```js
+/**
+ * @param {number[]} rating
+ * @return {number}
+ */
+var numTeams = function (rating) {
+    const n = rating.length;
+    const f = {
+        asc: Array.from({ length: n }, () => Array(3).fill(-1)),
+        desc: Array.from({ length: n }, () => Array(3).fill(-1)),
+    };
+
+    const fn = (i, available, type) => {
+        if (!available) {
+            return 1;
+        }
+        if (f[type][i][available] !== -1) {
+            return f[type][i][available];
+        }
+
+        let ans = 0;
+        for (let j = i + 1; j < n; j++) {
+            if (rating[j] > rating[i]) {
+                if (type === 'asc') {
+                    ans += fn(j, available - 1, 'asc');
+                }
+            } else {
+                if (type === 'desc') {
+                    ans += fn(j, available - 1, 'desc');
+                }
+            }
+        }
+        f[type][i][available] = ans;
+
+        return ans;
+    };
+
+    let ans = 0;
+    for (let i = 0; i < n; i++) {
+        ans += fn(i, 2, 'asc') + fn(i, 2, 'desc');
+    }
+
+    return ans;
+};
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

solution/1300-1399/1395.Count Number of Teams/Solution3.js

@@ -0,0 +1,43 @@
+/**
+ * @param {number[]} rating
+ * @return {number}
+ */
+var numTeams = function (rating) {
+    const n = rating.length;
+    const f = {
+        asc: Array.from({ length: n }, () => Array(3).fill(-1)),
+        desc: Array.from({ length: n }, () => Array(3).fill(-1)),
+    };
+
+    const fn = (i, available, type) => {
+        if (!available) {
+            return 1;
+        }
+        if (f[type][i][available] !== -1) {
+            return f[type][i][available];
+        }
+
+        let ans = 0;
+        for (let j = i + 1; j < n; j++) {
+            if (rating[j] > rating[i]) {
+                if (type === 'asc') {
+                    ans += fn(j, available - 1, 'asc');
+                }
+            } else {
+                if (type === 'desc') {
+                    ans += fn(j, available - 1, 'desc');
+                }
+            }
+        }
+        f[type][i][available] = ans;
+
+        return ans;
+    };
+
+    let ans = 0;
+    for (let i = 0; i < n; i++) {
+        ans += fn(i, 2, 'asc') + fn(i, 2, 'desc');
+    }
+
+    return ans;
+};