20231231 Finished

src/solution/mod.rs

@@ -10,3 +10,4 @@ mod s0052_n_queens_ii;
 mod s0912_sort_an_array;
 mod s1276_number_of_burgers_with_no_waste_of_ingredients;
 mod s0006_zigzag_conversion;
+mod s0007_reverse_integer;

src/solution/s0007_reverse_integer.rs

@@ -0,0 +1,66 @@
+/**
+ * [7] Reverse Integer
+ *
+ * Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-2^31, 2^31 - 1], then return 0.
+ * Assume the environment does not allow you to store 64-bit integers (signed or unsigned).
+ *  
+ * <strong class="example">Example 1:
+ * 
+ * Input: x = 123
+ * Output: 321
+ * 
+ * <strong class="example">Example 2:
+ * 
+ * Input: x = -123
+ * Output: -321
+ * 
+ * <strong class="example">Example 3:
+ * 
+ * Input: x = 120
+ * Output: 21
+ * 
+ *  
+ * Constraints:
+ * 
+ * 	-2^31 <= x <= 2^31 - 1
+ * 
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.cn/problems/reverse-integer/
+// discuss: https://leetcode.cn/problems/reverse-integer/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn reverse(x: i32) -> i32 {
+        let (num, negative) = if x < 0 {
+            (-x, true)
+        } else {
+            (x, false)
+        };
+
+        let str = num.to_string();
+        let mut str: String = str.chars().rev().collect();
+        if negative {
+            str.insert(0, '-');
+        }
+
+        str.parse::<i32>().unwrap_or_else(|_| 0)
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_7() {
+        assert_eq!(321, Solution::reverse(123));
+        assert_eq!(-321, Solution::reverse(-123));
+        assert_eq!(21, Solution::reverse(120));
+        assert_eq!(0, Solution::reverse(0));
+    }
+}