#1850
Minimum Adjacent Swaps to Reach the Kth Smallest Number
pupil · 545 · lc medium +28 · verified · 72% accepted · 808 likes · top 81%
Description
Given a string num representing a large integer and an integer k, call an integer wonderful if it is a permutation of num's digits with a strictly greater value. Among all wonderful integers, focus on the k-th smallest.
Return the minimum number of adjacent digit swaps needed to transform num into that value.
Example 1:
Input: num = "5489355142", k = 4
Output: 2
Explanation: The 4th smallest wonderful number is "5489355421". To get this number:
- Swap index 7 with index 8: "5489355142" -> "5489355412"
- Swap index 8 with index 9: "5489355412" -> "5489355421"
Example 2:
Input: num = "11112", k = 4
Output: 4
Explanation: The 4th smallest wonderful number is "21111". To get this number:
- Swap index 3 with index 4: "11112" -> "11121"
- Swap index 2 with index 3: "11121" -> "11211"
- Swap index 1 with index 2: "11211" -> "12111"
- Swap index 0 with index 1: "12111" -> "21111"
Example 3:
Input: num = "00123", k = 1
Output: 1
Explanation: The 1st smallest wonderful number is "00132". To get this number:
- Swap index 3 with index 4: "00123" -> "00132"
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