OneTaskBy Tim King · Updated
Word Ladder Solver
Shortest One-Letter-at-a-Time Path Between Two Words, With Real Words
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How the Word Ladder Solver works
This word ladder solver finds the shortest chain from one word to another, changing a single letter at each step so every rung is a real word. Type a start and end word of the same length to see the fewest steps needed and several different ladders that reach it.
How the word ladder solver finds the shortest path
It treats every word of the same length as a point and links words that differ by one letter. A breadth-first search spreads out from the start word one step at a time, so the first time it reaches the end word it has found the shortest ladder. It also counts how many different ladders share that length.
A puzzle with history
Lewis Carroll invented the game in 1877 and called it Doublets. His classic example turns HEAD into TAIL, and he challenged readers to drive PIG into STY. The puzzle is also known as word golf or word links, and it is still used in classrooms to practise spelling.
When no ladder exists
Some words have no neighbours at all, and some form small islands that never connect to the rest. If there is no path, the solver says so. Longer words are more often stranded, since fewer seven or eight-letter words differ by just one letter.
FAQ
Why does it show more than one ladder?
Many word pairs can be joined by several routes of the same length. The solver shows up to six of them and tells you how many exist in total, which is useful when you are setting a puzzle and want a unique answer.
Can the words be different lengths?
No. A classic word ladder only changes letters, never adds or removes them, so both words must be the same length. Variants that allow adding letters exist, but this solver sticks to the original rules.
How long can the words be?
Two to eight letters. Most interesting ladders use three to five-letter words, where there are plenty of neighbours and paths are usually four to eight steps long.
See also: all Puzzle Solvers tools, Scrabble & Board Games, Anagrams & Rhymes, Puzzle Makers.
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