diff --git a/src/arr.rs b/src/arr.rs
index 5a21a23..f66682c 100644
--- a/src/arr.rs
+++ b/src/arr.rs
@@ -13,13 +13,63 @@ pub fn make_arr(s: &str) -> Vec<i32> {
 }
 
 pub fn make_matrix(s: &str) -> Vec<Vec<i32>> {
-    s.trim_matches(&['[', ']'][..])
-        .split("],[")
-        .map(|row| {
-            row.trim_matches(&['[', ']'][..])
-                .split(',')
-                .map(|x| x.trim().parse::<i32>().unwrap())
-                .collect()
-        })
-        .collect()
+    let s = s.trim();
+
+    // Remove only the outermost pair of brackets if present, e.g. "[[1,2],[3,4]]" -> "[1,2],[3,4]"
+    let inner = if s.len() >= 2 && s.starts_with('[') && s.ends_with(']') {
+        &s[1..s.len() - 1]
+    } else {
+        s
+    }
+    .trim();
+
+    if inner.is_empty() {
+        return Vec::new();
+    }
+
+    let bytes = inner.as_bytes();
+    let mut i = 0usize;
+    let mut rows: Vec<Vec<i32>> = Vec::new();
+    while i < bytes.len() {
+        // find next '['
+        while i < bytes.len() && bytes[i] != b'[' {
+            i += 1;
+        }
+        if i >= bytes.len() {
+            break;
+        }
+        let start = i + 1; // byte index after '['
+        i = start;
+        // find matching ']'
+        while i < bytes.len() && bytes[i] != b']' {
+            i += 1;
+        }
+        let end = i; // exclusive
+        // move i past ']' for next iteration (if in bounds)
+        if i < bytes.len() {
+            i += 1;
+        }
+
+        if end <= start {
+            // empty row like []
+            rows.push(Vec::new());
+            continue;
+        }
+
+        let row_str = &inner[start..end];
+        let row_vec: Vec<i32> = row_str
+            .split(',')
+            .map(|x| {
+                let x = x.trim();
+                if x == "null" || x.is_empty() {
+                    -1
+                } else {
+                    x.parse::<i32>().unwrap()
+                }
+            })
+            .collect();
+        rows.push(row_vec);
+    }
+
+    rows
 }
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index fbb6022..25971f0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,26 +1,71 @@
 mod arr;
-struct Solution {}
+struct Bank {
+    _balance: Vec<i64>,
+}
 
-impl Solution {
-    pub fn number_of_beams(bank: Vec<String>) -> i32 {
-        let mut ans = 0;
-        let mut last_ones = 0;
-        for i in 0..bank.len() {
-            let new_ones = bank[i].chars().fold(0,|last, c| last + if c == '1'{1}else {0});
-            if new_ones == 0 {
-                continue;
-            }
-            ans += last_ones * new_ones;
-            last_ones = new_ones;
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl Bank {
+
+    fn new(balance: Vec<i64>) -> Self {
+        Bank { _balance: balance }
+    }
+
+    fn valid(&self, account: i32,money: i64) -> bool {
+        account > 0 && account as usize <= self._balance.len() && self._balance[account as usize - 1] >= money
+    }
+    fn transfer(&mut self, account1: i32, account2: i32, money: i64) -> bool {
+        if !self.valid(account1, money) {
+            return false;
+        }
+        self._balance[account1 as usize - 1] -= money;
+        self._balance[account2 as usize - 1] += money;
+        true
+    }
+
+    fn deposit(&mut self, account: i32, money: i64) -> bool {
+        if !self.valid(account, 0) {
+            return false;
+        }
+        self._balance[account as usize - 1] += money;
+        true
+    }
+
+    fn withdraw(&mut self, account: i32, money: i64) -> bool {
+        if !self.valid(account, money) {
+            false
+        } else {
+            self._balance[account as usize - 1] -= money;
+            true
         }
-        ans
     }
 }
 
+/**
+ * Your Bank object will be instantiated and called as such:
+ * let obj = Bank::new(balance);
+ * let ret_1: bool = obj.transfer(account1, account2, money);
+ * let ret_2: bool = obj.deposit(account, money);
+ * let ret_3: bool = obj.withdraw(account, money);
+ */
+
 fn main() {
-    let src = vec!["011001", "000000", "010100", "001000"]
-        .iter()
-        .map(|s| s.to_string())
-        .collect();
-    println!("{:?}", Solution::number_of_beams(src));
+    let oper = ["withdraw", "transfer", "deposit", "transfer", "withdraw"];
+    let val = arr::make_matrix("[[3, 10], [5, 1, 20], [5, 20], [3, 4, 15], [10, 50]]");
+    //输出：
+    //[true, true, true, false, false]
+    let mut bank = Bank::new(vec![10, 100, 20, 50, 30]);
+    for i in 0..oper.len() {
+        let result = match oper[i] {
+            "withdraw" => bank.withdraw(val[i][0], val[i][1] as i64),
+            "transfer" => bank.transfer(val[i][0], val[i][1], val[i][2] as i64),
+            "deposit" => bank.deposit(val[i][0], val[i][1] as i64),
+            _ => false,
+        };
+        println!("{}", result);
+    }
+
 }