Solved 1012

Author: guangsheng.li01

src/a1012_numbers_with_repeated_digits.rs

@@ -0,0 +1,81 @@
+/*
+ * [1012] numbers-with-repeated-digits
+ */
+
+pub struct Solution {}
+
+// solution impl starts here
+
+impl Solution {
+    pub fn num_dup_digits_at_most_n(n: i32) -> i32 {
+        n - Self::digit_dp(n)
+    }
+
+    fn digit_dp(n: i32) -> i32 {
+        let mut n = n;
+        let mut digits = Vec::new();
+        while n > 0 {
+            digits.push(n % 10);
+            n /= 10;
+        }
+        let k = digits.len();
+
+        let mut used: [i32; 10] = [0; 10];
+        let mut total = 0;
+
+        for i in 1..k {
+            total += 9 * Self::a(9, i as i32 - 1);
+        }
+
+        for i in 0..k {
+            let i = k - 1 - i;
+            let num = digits[i];
+
+            for j in (if i == k - 1 { 1 } else { 0 })..num {
+                if used[j as usize] != 0 {
+                    continue;
+                }
+                total += Self::a((10 - k + i) as i32, i as i32);
+            }
+
+            used[num as usize] += 1;
+            if used[num as usize] > 1 {
+                break;
+            }
+
+            if i == 0 {
+                total += 1;
+            }
+        }
+
+        total
+    }
+
+    fn a(a: i32, b: i32) -> i32 {
+        Self::fact(a) / Self::fact(a - b)
+    }
+
+    fn fact(n: i32) -> i32 {
+        if n == 0 || n == 1 {
+            return 1;
+        }
+        return n * Self::fact(n - 1);
+    }
+}
+// solution impl ends here
+
+// solution tests starts here
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_case0() {
+        assert_eq!(Solution::num_dup_digits_at_most_n(20), 1);
+        assert_eq!(Solution::num_dup_digits_at_most_n(100), 10);
+        assert_eq!(Solution::num_dup_digits_at_most_n(1000), 262);
+    }
+}
+
+// solution tests ends here

src/lib.rs

@@ -38,6 +38,7 @@ mod a0937_reorder_data_in_log_files;
 mod a0949_largest_time_for_given_digits;
 mod a0973_k_closest_points_to_origin;
 mod a0980_unique_paths_iii;
+mod a1012_numbers_with_repeated_digits;
 mod a1018_binary_prefix_divisible_by_5;
 mod a1021_remove_outermost_parentheses;
 mod a1047_remove_all_adjacent_duplicates_in_string;