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

Author: rain84

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

@@ -527,4 +527,60 @@ function numTeams(rating: number[]): number {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### Solution 3: Recursion + Memoization
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+function numTeams(rating: number[]): number {
+    const n = rating.length;
+    const f: Record<Type, number[][]> = {
+        asc: Array.from({ length: n }, () => Array(3).fill(-1)),
+        desc: Array.from({ length: n }, () => Array(3).fill(-1)),
+    };
+
+    const fn = (i: number, available: number, type: 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;
+}
+
+type Type = 'asc' | 'desc';
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->

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

@@ -37,7 +37,7 @@ tags:
 <pre>
 <strong>Input:</strong> rating = [2,5,3,4,1]
 <strong>Output:</strong> 3
-<strong>Explanation:</strong> We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1). 
+<strong>Explanation:</strong> We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1).
 </pre>
 
 <p><strong class="example">Example 2:</strong></p>
@@ -525,4 +525,60 @@ function numTeams(rating: number[]): number {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### Solution 3: Recursion + Memoization
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+function numTeams(rating: number[]): number {
+    const n = rating.length;
+    const f: Record<Type, number[][]> = {
+        asc: Array.from({ length: n }, () => Array(3).fill(-1)),
+        desc: Array.from({ length: n }, () => Array(3).fill(-1)),
+    };
+
+    const fn = (i: number, available: number, type: 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;
+}
+
+type Type = 'asc' | 'desc';
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->

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

@@ -0,0 +1,41 @@
+function numTeams(rating: number[]): number {
+    const n = rating.length;
+    const f: Record<Type, number[][]> = {
+        asc: Array.from({ length: n }, () => Array(3).fill(-1)),
+        desc: Array.from({ length: n }, () => Array(3).fill(-1)),
+    };
+
+    const fn = (i: number, available: number, type: 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;
+}
+
+type Type = 'asc' | 'desc';