LeetCode-in-Java
3265. Count Almost Equal Pairs I
Medium
You are given an array nums consisting of positive integers.
We call two integers x and y in this problem almost equal if both integers can become equal after performing the following operation at most once:
- Choose either
xoryand swap any two digits within the chosen number.
Return the number of indices i and j in nums where i < j such that nums[i] and nums[j] are almost equal.
Note that it is allowed for an integer to have leading zeros after performing an operation.
Example 1:
Input: nums = [3,12,30,17,21]
Output: 2
Explanation:
The almost equal pairs of elements are:
- 3 and 30. By swapping 3 and 0 in 30, you get 3.
- 12 and 21. By swapping 1 and 2 in 12, you get 21.
Example 2:
Input: nums = [1,1,1,1,1]
Output: 10
Explanation:
Every two elements in the array are almost equal.
Example 3:
Input: nums = [123,231]
Output: 0
Explanation:
We cannot swap any two digits of 123 or 231 to reach the other.
Constraints:
2 <= nums.length <= 1001 <= nums[i] <= 106
Solution
public class Solution {
public int countPairs(int[] nums) {
int ans = 0;
for (int i = 0; i < nums.length - 1; i++) {
for (int j = i + 1; j < nums.length; j++) {
if (nums[i] == nums[j]
|| ((nums[j] - nums[i]) % 9 == 0 && check(nums[i], nums[j]))) {
ans++;
}
}
}
return ans;
}
private boolean check(int a, int b) {
int[] ca = new int[10];
int[] cb = new int[10];
int d = 0;
while (a > 0 || b > 0) {
if (a % 10 != b % 10) {
d++;
if (d > 2) {
return false;
}
}
ca[a % 10]++;
cb[b % 10]++;
a /= 10;
b /= 10;
}
return d == 2 && areEqual(ca, cb);
}
private boolean areEqual(int[] a, int[] b) {
for (int i = 0; i < 10; i++) {
if (a[i] != b[i]) {
return false;
}
}
return true;
}
}