diff --git a/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README.md b/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README.md
index ff2247333b1d2..4dc990799659f 100644
--- a/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README.md	
+++ b/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README.md	
@@ -156,10 +156,10 @@ func largestInteger(num int) int {
 
 ```ts
 function largestInteger(num: number): number {
-    let arrs = String(num).split('').map(Number);
-    let odds = []; // 奇数
-    let evens = [];
-    for (let i of arrs) {
+    const arrs: number[] = String(num).split('').map(Number);
+    const odds: number[] = []; // 奇数
+    const evens: number[] = [];
+    for (const i of arrs) {
         if ((i & 1) == 1) {
             odds.push(i);
         } else {
@@ -168,9 +168,9 @@ function largestInteger(num: number): number {
     }
     odds.sort((a, b) => a - b);
     evens.sort((a, b) => a - b);
-    let ans = [];
-    for (let i of arrs) {
-        ans.push((i & 1) == 1 ? odds.pop() : evens.pop());
+    const ans: number[] = [];
+    for (const i of arrs) {
+        ans.push((i & 1) === 1 ? odds.pop() : evens.pop());
     }
     return Number(ans.join(''));
 }
diff --git a/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README_EN.md b/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README_EN.md
index ecee25f315af7..85007dcfb7496 100644
--- a/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README_EN.md	
+++ b/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/README_EN.md	
@@ -154,10 +154,10 @@ func largestInteger(num int) int {
 
 ```ts
 function largestInteger(num: number): number {
-    let arrs = String(num).split('').map(Number);
-    let odds = []; // 奇数
-    let evens = [];
-    for (let i of arrs) {
+    const arrs: number[] = String(num).split('').map(Number);
+    const odds: number[] = []; // 奇数
+    const evens: number[] = [];
+    for (const i of arrs) {
         if ((i & 1) == 1) {
             odds.push(i);
         } else {
@@ -166,9 +166,9 @@ function largestInteger(num: number): number {
     }
     odds.sort((a, b) => a - b);
     evens.sort((a, b) => a - b);
-    let ans = [];
-    for (let i of arrs) {
-        ans.push((i & 1) == 1 ? odds.pop() : evens.pop());
+    const ans: number[] = [];
+    for (const i of arrs) {
+        ans.push((i & 1) === 1 ? odds.pop() : evens.pop());
     }
     return Number(ans.join(''));
 }
diff --git a/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/Solution.ts b/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/Solution.ts
index c877f9280dc07..e47f870abbd37 100644
--- a/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/Solution.ts	
+++ b/solution/2200-2299/2231.Largest Number After Digit Swaps by Parity/Solution.ts	
@@ -1,8 +1,8 @@
 function largestInteger(num: number): number {
-    let arrs = String(num).split('').map(Number);
-    let odds = []; // 奇数
-    let evens = [];
-    for (let i of arrs) {
+    const arrs: number[] = String(num).split('').map(Number);
+    const odds: number[] = []; // 奇数
+    const evens: number[] = [];
+    for (const i of arrs) {
         if ((i & 1) == 1) {
             odds.push(i);
         } else {
@@ -11,9 +11,9 @@ function largestInteger(num: number): number {
     }
     odds.sort((a, b) => a - b);
     evens.sort((a, b) => a - b);
-    let ans = [];
-    for (let i of arrs) {
-        ans.push((i & 1) == 1 ? odds.pop() : evens.pop());
+    const ans: number[] = [];
+    for (const i of arrs) {
+        ans.push((i & 1) === 1 ? odds.pop() : evens.pop());
     }
     return Number(ans.join(''));
 }