Java Challenge - sumDigits Recursive

Given a non-negative int n, return the sum of its digits recursively (no loops). Note that mod (%) by 10 yields the rightmost digit (126 % 10 is 6), while divide (/) by 10 removes the rightmost digit (126 / 10 is 12). sumDigits(126) → 9 sumDigits(49) → 13 sumDigits(12) → 3

Hisoka's Trick :

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public int sumDigits(int n) { if(n < 10) return n; return n%10 + sumDigits(n/10); }

Test Result:

Java Challenge - Triangle Recursive

We have triangle made of blocks. The topmost row has 1 block, the next row down has 2 blocks, the next row has 3 blocks, and so on. Compute recursively (no loops or multiplication) the total number of blocks in such a triangle with the given number of rows.

triangle(0) → 0
triangle(1) → 1
triangle(2) → 3

Hisoka :

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public int triangle(int rows) { if (rows == 0) return 0; return rows+triangle(rows-1); }

Test Result: