# Commits

committed f78ef4e

# docs/Nurikabe_Strategies.txt

` limits of its number), an island can only expand into one cell, then that`
` cell will be white.`
` `
`-#. If an Island reaches certain points that reaching them consumes all of its`
`+#. If an Island reaches certain points which consume all of its`
` number, then its white edge points can be marked with black in the opposite`
` direction to its extent.`
` `
` We can see that the island should expand into the leftmost gray/unknown cell `
` or else it will need to take a costly detour which will consume the rest of its`
` number.`
`+`
`+#. Islands that can expand in several different manners must mark all the `
`+common black cells inflected by these ways in this way. For example:`
`+`
`++------`
`+|[2][G]`
`+|[G][G]`
`+`
`+The lower-right [G] cell must be black because it will be black whether the`
`+2 expands to the right or to the bottom.`
`+`
`+In addition, if we have:`
`+`
`+    x1 x2 x3 x4 `
`+y1     [B][B][B]`
`+y2  [B][4][W][B]`
`+y3  [B][G][W][B]`
`+y4     [G][G][B]`
`+`
`+The the 4-cell region can only expand into (x2,y3) or (x3,y4) so `
`+[G](x2,y4) must be black.`
`+`