Death by Sudoku Read Online Free Page B

numbers one through nine. Based on the given numbers, Liza had to figure out the one and only solution that fit the pattern. Some people called sudoku a “numbers crossword” or a math puzzle. But there was no number crunching involved. This was an exercise in pure logic.
    Liza began to scan the entire puzzle. Look at the forest,
not the trees , she told herself, running her eyes over the sets of boxes, both across and down.
    It was hard to miss the combination of 7s in the top tier of boxes. These numbers appeared in the first row of the first box and in the third row of the third box. That meant there had to be a 7 in the middle row of the middle box. Only two of the three spaces were available—an 8 occupied the center space. Four spaces down from the left-hand space was a 7, eliminating that open cell as a candidate. So there was only one solution. Liza picked up her pen and entered a 7 to the puzzle.
    The second tier of boxes also had two spaces occupied by 7s. From their placement (and the fact that there was a 7 in the first vertical column), that meant a 7 could only appear in the right-hand space on the middle row of the left center box. Checking the bottom tier, Liza cross-checked
the rows and columns and found that the existing 7s ruled out all the spaces in the bottom row except for one. She quickly penned 7 in that remaining box.
    Three down, forty-something to go , Liza thought as she found another cue in the lower tier of boxes. The number 2 appeared in the first row across and the third. Cross-checking the columns for the available spaces forced another solution.
    Soon enough, however, she’d found all the obvious matchups. Then her pencil came into play, listing the possible candidate numbers to fill each empty space. It became a process of elimination, zooming in to cross-check spaces with the least numbers of candidates, then zooming out to see how each solution affected the puzzle as a whole. Each time she placed a number in ink, the circle of unknowns shrank.
    Liza frowned. She was moving right along—too fast, in fact. What was Will up to with this puzzle? She found herself solving it with the simplest techniques in her arsenal—the kind of stuff that Hank was reading in his Nincompoops sudoku book. Easy logic quickly uncovered some candidates—and just as quickly eliminated others. Where were the really tricky moves—the X-wing solutions depending on four spaces at once, the Swordfish configurations that rested on six?
    If Will had a real brain-buster up his sleeve, it should have shown by now , Liza thought worriedly. I’m running out of spaces with candidates.
    But no last-minute brilliance in puzzle development appeared. The number of spaces with more than one candidate kept contracting, right down to a final set of solutions.
    Liza took a long, deep breath, almost a snort. Maybe it was too easy, but it was a definite solution. She pushed all niggling doubts aside and began checking for any errors. Her focus was now entirely on the sheet of paper before her. The digital display and the murmurs from the proctors and onlookers receded from her consciousness.
    But Liza came back to the world with a thump—an audible thump, she suddenly realized. Liza looked over her shoulder to see Hank, his face shining, sitting up straight and holding out his puzzle. One of the proctors took the paper and brought it up to Will. After studying it for a moment, he shook his head. “I’m sorry, this is not correct.”
    Hank’s face crumpled. “I—I—” He rose from his seat and slunk from the Irvine Room, blinking back tears.
    Probably didn’t double-check his solution , Liza thought as she began that very process on her puzzle. A painstaking recap through every space in each row, column, and box could take minutes. But it could also avoid a careless—and disastrous—mistake. Liza looked down at her solution. It was ready.
    Silently, she turned her puzzle sheet over. A proctor instantly whisked it