solve #179

Author: aylei

src/lib.rs

@@ -161,3 +161,4 @@ mod n0171_excel_sheet_column_number;
 mod n0172_factorial_trailing_zeroes;
 mod n0173_binary_search_tree_iterator;
 mod n0174_dungeon_game;
+mod n0179_largest_number;

src/n0179_largest_number.rs

@@ -0,0 +1,50 @@
+/**
+ * [179] Largest Number
+ *
+ * Given a list of non negative integers, arrange them such that they form the largest number.
+ * 
+ * Example 1:
+ * 
+ * 
+ * Input: [10,2]
+ * Output: "210"
+ * 
+ * Example 2:
+ * 
+ * 
+ * Input: [3,30,34,5,9]
+ * Output: "9534330"
+ * 
+ * 
+ * Note: The result may be very large, so you need to return a string instead of an integer.
+ * 
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn largest_number(nums: Vec<i32>) -> String {
+        let mut nums = nums.into_iter().map(|num| {num.to_string()}).collect::<Vec<_>>();
+        nums.sort_unstable_by(|a, b| {
+            format!("{}{}", b, a).cmp(&format!("{}{}", a, b))
+        });
+        if nums[0] == "0" { return "0".to_owned() }
+        nums.iter().fold(String::new(), |mut s, num| {
+            s.push_str(num); s
+        })
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_179() {
+        assert_eq!(Solution::largest_number(vec![3,30,34,5,9]), "9534330".to_owned());
+        assert_eq!(Solution::largest_number(vec![121,12]), "12121".to_owned());
+    }
+}