The following puzzles were created by Zack Butler, a member of the US team that won the 1999 World Puzzle Championship in Budapest. Complete the 9 by 9 table below, so that every digit from 1 to 9 appears once in each column, once in each row, and once in each of the 3 by 3 squares that have been marked off.
Puzzle 1:
+---+---+---+---+---+---+---+---+---+
| : : | : : 9 | : : 7 |
+ . . . . . + . . . . . + . . . . . +
| 8 : : 7 | : : | : 3 : |
+ . . . . . + . . . . . + . . . . . +
| 3 : 9 : 2 | : : 5 | : : 6 |
+---+---+---+---+---+---+---+---+---+
| : : 9 | : : 3 | : 4 : |
+ . . . . . + . . . . . + . . . . . +
| 2 : 6 : | : : | : 7 : 5 |
+ . . . . . + . . . . . + . . . . . +
| : 4 : | 6 : : | 2 : : |
+---+---+---+---+---+---+---+---+---+
| 9 : : | 4 : : | 1 : 2 : 8 |
+ . . . . . + . . . . . + . . . . . +
| : 8 : | : : | 5 : : 4 |
+ . . . . . + . . . . . + . . . . . +
| 6 : : | 5 : : | : : |
+---+---+---+---+---+---+---+---+---+
Puzzle 2:
+---+---+---+---+---+---+---+---+---+
| : : 2 | : 7 : 5 | : 8 : |
+ . . . . . + . . . . . + . . . . . +
| : : 3 | 1 : : | : 4 : |
+ . . . . . + . . . . . + . . . . . +
| : : 6 | 3 : : 8 | 9 : : 2 |
+---+---+---+---+---+---+---+---+---+
| : : | 5 : : | : : |
+ . . . . . + . . . . . + . . . . . +
| : 6 : 1 | 4 : : 2 | 7 : 3 : |
+ . . . . . + . . . . . + . . . . . +
| : : | : : 6 | : : |
+---+---+---+---+---+---+---+---+---+
| 2 : : 8 | 9 : : 4 | 5 : : |
+ . . . . . + . . . . . + . . . . . +
| : 7 : | : : 1 | 3 : : |
+ . . . . . + . . . . . + . . . . . +
| : 4 : | 7 : 5 : | 8 : : |
+---+---+---+---+---+---+---+---+---+
This sort of puzzle has been popular in Japan under the name "Sudoku", and has lately become a craze in Britain, with daily puzzles being published in newspapers, and now in USA Today.
I give up, show me the solution.