Pairs a[i] == b[j], i * j % k == 0 #easy


https://leetcode.com/problems/count-equal-and-divisible-pairs-in-an-array/description/

https://leetcode.com/problems/count-largest-group/description/


Count of max groups by digits sum 1..n #easy

3-subarrays 2a + 2c == b #easy


https://leetcode.com/problems/count-subarrays-of-length-three-with-a-condition/description/

https://leetcode.com/problems/find-numbers-with-even-number-of-digits/description/


Even length numbers #easy

Dominoes pairs #easy #hash

https://leetcode.com/problems/number-of-equivalent-domino-pairs/description/

n[n[i]] #easy


https://leetcode.com/problems/build-array-from-permutation/description/

3 odds #easy #bitmask


https://leetcode.com/problems/three-consecutive-odds/description/

Triple digit even numbers from digits #easy #backtrack


https://leetcode.com/problems/finding-3-digit-even-numbers/description

https://leetcode.com/problems/longest-unequal-adjacent-groups-subsequence-i/description


Longest subsequence alterating g #easy #gready

https://leetcode.com/problems/type-of-triangle/description/

Triangle type by lengths #easy