diff --git a/notes/剑指 offer 题解.md b/notes/剑指 offer 题解.md
index 9e7e6d94..01f25e6a 100644
--- a/notes/剑指 offer 题解.md	
+++ b/notes/剑指 offer 题解.md	
@@ -624,26 +624,33 @@ private char[][] buildMatrix(char[] array) {
 ```java
 private int cnt = 0;
 private int[][] next = {{0, -1}, {0, 1}, {-1, 0}, {1, 0}};
+private int rows;
+private int cols;
+private int threshold;
 private int[][] digitSum;
 
 public int movingCount(int threshold, int rows, int cols) {
-    initDigitSum(rows, cols);
-    dfs(new boolean[rows][cols], threshold, rows, cols, 0, 0);
+    this.rows = rows;
+    this.cols = cols;
+    this.threshold = threshold;
+    initDigitSum();
+    boolean[][] hasVisited = new boolean[rows][cols];
+    dfs(hasVisited, 0, 0);
     return cnt;
 }
 
-private void dfs(boolean[][] visited, int threshold, int rows, int cols, int r, int c) {
-    if (r < 0 || r >= rows || c < 0 || c >= cols) return;
-    if (visited[r][c]) return;
-    visited[r][c] = true;
-    if (this.digitSum[r][c] > threshold) return;
+private void dfs(boolean[][] hasVisited, int r, int c) {
+    if (r < 0 || r >= this.rows || c < 0 || c >= this.cols) return;
+    if (hasVisited[r][c]) return;
+    hasVisited[r][c] = true;
+    if (this.digitSum[r][c] > this.threshold) return;
     this.cnt++;
     for (int i = 0; i < this.next.length; i++) {
-        dfs(visited, threshold, rows, cols, r + next[i][0], c + next[i][1]);
+        dfs(hasVisited, r + next[i][0], c + next[i][1]);
     }
 }
 
-private void initDigitSum(int rows, int cols) {
+private void initDigitSum() {
     int[] digitSumOne = new int[Math.max(rows, cols)];
     for (int i = 0; i < digitSumOne.length; i++) {
         int n = i;
@@ -653,8 +660,8 @@ private void initDigitSum(int rows, int cols) {
         }
     }
     this.digitSum = new int[rows][cols];
-    for (int i = 0; i < rows; i++) {
-        for (int j = 0; j < cols; j++) {
+    for (int i = 0; i < this.rows; i++) {
+        for (int j = 0; j < this.cols; j++) {
             this.digitSum[i][j] = digitSumOne[i] + digitSumOne[j];
         }
     }