feat: update js solution to lc problem: No.0017

Author: rain84

solution/0000-0099/0017.Letter Combinations of a Phone Number/README.md

@@ -397,24 +397,17 @@ function letterCombinations(digits: string): string[] {
     }
     const ans: string[] = [];
     const n = digits.length;
-    const map: Record<string, string[]> = {
-        2: [...'abc'],
-        3: [...'def'],
-        4: [...'ghi'],
-        5: [...'jkl'],
-        6: [...'mno'],
-        7: [...'pqrs'],
-        8: [...'tuv'],
-        9: [...'wxyz'],
-    };
+    const d: string[][] = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'].map(x => [
+        ...x,
+    ]);
 
     const dfs = (curr: string, start: number) => {
         if (curr.length === n) {
             ans.push(curr);
             return;
         }
         for (let i = start; i < n; i++) {
-            for (const ch of map[digits[i]]) {
+            for (const ch of d[+digits[i] - 2]) {
                 dfs(curr + ch, i + 1);
             }
         }
@@ -462,25 +455,25 @@ impl Solution {
  * @return {string[]}
  */
 var letterCombinations = function (digits) {
-    if (digits.length == 0) {
+    if (digits.length === 0) {
         return [];
     }
     const ans = [];
-    const t = [];
-    const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
-    const dfs = i => {
-        if (i >= digits.length) {
-            ans.push(t.join(''));
+    const n = digits.length;
+    const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'].map(x => [...x]);
+
+    const dfs = (curr, start) => {
+        if (curr.length === n) {
+            ans.push(curr);
             return;
         }
-        const s = d[parseInt(digits[i]) - 2];
-        for (const c of s) {
-            t.push(c);
-            dfs(i + 1);
-            t.pop();
+        for (let i = start; i < n; i++) {
+            for (const ch of map[+digits[i] - 2]) {
+                dfs(curr + ch, i + 1);
+            }
         }
     };
-    dfs(0);
+    dfs('', 0);
     return ans;
 };
 ```

solution/0000-0099/0017.Letter Combinations of a Phone Number/README_EN.md

@@ -393,31 +393,24 @@ function letterCombinations(digits: string): string[] {
     }
     const ans: string[] = [];
     const n = digits.length;
-    const map: Record<string, string[]> = {
-        2: [...'abc'],
-        3: [...'def'],
-        4: [...'ghi'],
-        5: [...'jkl'],
-        6: [...'mno'],
-        7: [...'pqrs'],
-        8: [...'tuv'],
-        9: [...'wxyz'],
-    };
+    const d: string[][] = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'].map(x => [
+        ...x,
+    ]);
+
     const dfs = (curr: string, start: number) => {
         if (curr.length === n) {
             ans.push(curr);
             return;
         }
         for (let i = start; i < n; i++) {
-            for (const ch of map[digits[i]]) {
+            for (const ch of d[+digits[i] - 2]) {
                 dfs(curr + ch, i + 1);
             }
         }
     };
     dfs('', 0);
     return ans;
 }
-
 ```
 
 #### Rust
@@ -458,25 +451,25 @@ impl Solution {
  * @return {string[]}
  */
 var letterCombinations = function (digits) {
-    if (digits.length == 0) {
+    if (digits.length === 0) {
         return [];
     }
     const ans = [];
-    const t = [];
-    const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
-    const dfs = i => {
-        if (i >= digits.length) {
-            ans.push(t.join(''));
+    const n = digits.length;
+    const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'].map(x => [...x]);
+
+    const dfs = (curr, start) => {
+        if (curr.length === n) {
+            ans.push(curr);
             return;
         }
-        const s = d[parseInt(digits[i]) - 2];
-        for (const c of s) {
-            t.push(c);
-            dfs(i + 1);
-            t.pop();
+        for (let i = start; i < n; i++) {
+            for (const ch of map[+digits[i] - 2]) {
+                dfs(curr + ch, i + 1);
+            }
         }
     };
-    dfs(0);
+    dfs('', 0);
     return ans;
 };
 ```

solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution2.js

@@ -3,24 +3,24 @@
  * @return {string[]}
  */
 var letterCombinations = function (digits) {
-    if (digits.length == 0) {
+    if (digits.length === 0) {
         return [];
     }
     const ans = [];
-    const t = [];
-    const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
-    const dfs = i => {
-        if (i >= digits.length) {
-            ans.push(t.join(''));
+    const n = digits.length;
+    const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'].map(x => [...x]);
+
+    const dfs = (curr, start) => {
+        if (curr.length === n) {
+            ans.push(curr);
             return;
         }
-        const s = d[parseInt(digits[i]) - 2];
-        for (const c of s) {
-            t.push(c);
-            dfs(i + 1);
-            t.pop();
+        for (let i = start; i < n; i++) {
+            for (const ch of map[+digits[i] - 2]) {
+                dfs(curr + ch, i + 1);
+            }
         }
     };
-    dfs(0);
+    dfs('', 0);
     return ans;
 };

solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution2.ts

@@ -4,24 +4,17 @@ function letterCombinations(digits: string): string[] {
     }
     const ans: string[] = [];
     const n = digits.length;
-    const map: Record<string, string[]> = {
-        2: [...'abc'],
-        3: [...'def'],
-        4: [...'ghi'],
-        5: [...'jkl'],
-        6: [...'mno'],
-        7: [...'pqrs'],
-        8: [...'tuv'],
-        9: [...'wxyz'],
-    };
+    const d: string[][] = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'].map(x => [
+        ...x,
+    ]);
 
     const dfs = (curr: string, start: number) => {
         if (curr.length === n) {
             ans.push(curr);
             return;
         }
         for (let i = start; i < n; i++) {
-            for (const ch of map[digits[i]]) {
+            for (const ch of d[+digits[i] - 2]) {
                 dfs(curr + ch, i + 1);
             }
         }