Curious Cheetah
Yakuso
Background
This puzzle was developed by Betrand Leplay and first appeared in the French puzzle magazine Multilogic; hence, despite its name, it appears to be of French origin.
Puzzle and Goal
An unsolved puzzle consists of a rectangular grid. Some of the cells in the last row contain sums of the numbers in the same column; some of the other cells contain numbered clues.
The goal is to fill in all but the bottom row according to the rules.
Rules
The solved grid must satisfy the following conditions:
In a given row, only 0 or one other number N may appear; N must appear N times.
No number (other than 0) appears in any two rows. For instance, if there are four rows, 4 must appear four times in one row, 3 must appear three times in another row, and so on for 2 and 1.