Solve #264

Author: aylei

src/lib.rs

@@ -209,3 +209,4 @@ mod n0257_binary_tree_paths;
 mod n0258_add_digits;
 mod n0260_single_number_iii;
 mod n0263_ugly_number;
+mod n0264_ugly_number_ii;

src/n0264_ugly_number_ii.rs

@@ -0,0 +1,57 @@
+/**
+ * [264] Ugly Number II
+ *
+ * Write a program to find the n-th ugly number.
+ *
+ * Ugly numbers are positive numbers whose prime factors only include 2, 3, 5.
+ *
+ * Example:
+ *
+ *
+ * Input: n = 10
+ * Output: 12
+ * Explanation: 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 is the sequence of the first 10 ugly numbers.
+ *
+ * Note:
+ *
+ * <ol>
+ * 	1 is typically treated as an ugly number.
+ * 	n does not exceed 1690.
+ * </ol>
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn nth_ugly_number(n: i32) -> i32 {
+        let mut base2 = 0;
+        let mut base3 = 0;
+        let mut base5 = 0;
+        let mut ugly = vec![1;1];
+        for _ in 1..n {
+            let next2 = ugly[base2] * 2;
+            let next3 = ugly[base3] * 3;
+            let next5 = ugly[base5] * 5;
+            let next = i32::min(next2, i32::min(next3, next5));
+            if next2 == next { base2 += 1 }
+            if next3 == next { base3 += 1 }
+            if next5 == next { base5 += 1 }
+            ugly.push(next)
+        }
+        *ugly.last().unwrap()
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_264() {
+        assert_eq!(Solution::nth_ugly_number(1), 1);
+        assert_eq!(Solution::nth_ugly_number(10), 12);
+    }
+}