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feat: add js/ts solution to lc problem: No.1395 (#3349)
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‎solution/1300-1399/1395.Count Number of Teams/README.md

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Original file line numberDiff line numberDiff line change
@@ -527,4 +527,108 @@ function numTeams(rating: number[]): number {
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<!-- solution:end -->
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<!-- solution:start -->
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### 方法三：记忆化搜索
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<!-- tabs:start -->
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#### TypeScript
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```ts
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function numTeams(rating: number[]): number {
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const n = rating.length;
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const f: Record<Type, number[][]> = {
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asc: Array.from({ length: n }, () => Array(3).fill(-1)),
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desc: Array.from({ length: n }, () => Array(3).fill(-1)),
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};
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const fn = (i: number, available: number, type: Type) => {
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if (!available) {
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return 1;
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}
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if (f[type][i][available] !== -1) {
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return f[type][i][available];
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}
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let ans = 0;
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for (let j = i + 1; j < n; j++) {
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if (rating[j] > rating[i]) {
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if (type === 'asc') {
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ans += fn(j, available - 1, 'asc');
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}
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} else {
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if (type === 'desc') {
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ans += fn(j, available - 1, 'desc');
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}
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}
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}
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f[type][i][available] = ans;
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return ans;
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};
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let ans = 0;
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for (let i = 0; i < n; i++) {
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ans += fn(i, 2, 'asc') + fn(i, 2, 'desc');
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}
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return ans;
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}
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type Type = 'asc' | 'desc';
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```
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#### JavaScript
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```js
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/**
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* @param {number[]} rating
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* @return {number}
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*/
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var numTeams = function (rating) {
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const n = rating.length;
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const f = {
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asc: Array.from({ length: n }, () => Array(3).fill(-1)),
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desc: Array.from({ length: n }, () => Array(3).fill(-1)),
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};
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const fn = (i, available, type) => {
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if (!available) {
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return 1;
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}
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if (f[type][i][available] !== -1) {
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return f[type][i][available];
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}
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let ans = 0;
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for (let j = i + 1; j < n; j++) {
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if (rating[j] > rating[i]) {
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if (type === 'asc') {
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ans += fn(j, available - 1, 'asc');
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}
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} else {
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if (type === 'desc') {
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ans += fn(j, available - 1, 'desc');
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}
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}
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}
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f[type][i][available] = ans;
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return ans;
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};
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let ans = 0;
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for (let i = 0; i < n; i++) {
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ans += fn(i, 2, 'asc') + fn(i, 2, 'desc');
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}
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return ans;
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};
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```
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<!-- tabs:end -->
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<!-- solution:end -->
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<!-- problem:end -->

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

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@@ -37,7 +37,7 @@ tags:
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<pre>
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<strong>Input:</strong> rating = [2,5,3,4,1]
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<strong>Output:</strong> 3
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<strong>Explanation:</strong> We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1).
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<strong>Explanation:</strong> We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1).
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<!-- solution:end -->
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<!-- solution:start -->
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### Solution 3: Recursion + Memoization
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<!-- tabs:start -->
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#### TypeScript
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```ts
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function numTeams(rating: number[]): number {
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const n = rating.length;
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const f: Record<Type, number[][]> = {
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asc: Array.from({ length: n }, () => Array(3).fill(-1)),
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desc: Array.from({ length: n }, () => Array(3).fill(-1)),
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};
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const fn = (i: number, available: number, type: Type) => {
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if (!available) {
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return 1;
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}
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if (f[type][i][available] !== -1) {
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return f[type][i][available];
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}
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let ans = 0;
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for (let j = i + 1; j < n; j++) {
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if (rating[j] > rating[i]) {
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if (type === 'asc') {
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ans += fn(j, available - 1, 'asc');
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}
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} else {
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if (type === 'desc') {
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ans += fn(j, available - 1, 'desc');
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}
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}
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}
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f[type][i][available] = ans;
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return ans;
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};
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let ans = 0;
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for (let i = 0; i < n; i++) {
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ans += fn(i, 2, 'asc') + fn(i, 2, 'desc');
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}
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return ans;
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}
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type Type = 'asc' | 'desc';
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```
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#### JavaScript
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```js
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/**
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* @param {number[]} rating
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* @return {number}
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*/
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var numTeams = function (rating) {
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const n = rating.length;
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const f = {
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asc: Array.from({ length: n }, () => Array(3).fill(-1)),
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desc: Array.from({ length: n }, () => Array(3).fill(-1)),
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};
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const fn = (i, available, type) => {
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if (!available) {
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return 1;
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}
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if (f[type][i][available] !== -1) {
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return f[type][i][available];
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}
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let ans = 0;
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for (let j = i + 1; j < n; j++) {
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if (rating[j] > rating[i]) {
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if (type === 'asc') {
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ans += fn(j, available - 1, 'asc');
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}
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} else {
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if (type === 'desc') {
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ans += fn(j, available - 1, 'desc');
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}
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}
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}
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f[type][i][available] = ans;
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return ans;
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};
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let ans = 0;
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for (let i = 0; i < n; i++) {
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ans += fn(i, 2, 'asc') + fn(i, 2, 'desc');
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}
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return ans;
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};
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```
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<!-- tabs:end -->
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<!-- solution:end -->
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<!-- problem:end -->

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

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

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

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

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