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Suggestion to improve readability.

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chriseth 2018-02-09 17:49:50 +01:00 committed by Alex Beregszaszi
parent dc0a25f1cd
commit 12c3eb8880
1 changed files with 20 additions and 13 deletions
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27
libdevcore/StringUtils.cpp
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@ -53,23 +53,30 @@ size_t dev::stringDistance(string const& _str1, string const& _str2)
// In this dp formulation of Damerau–Levenshtein distance we are assuming that the strings are 1-based to make base case storage easier.
// So index accesser to _name1 and _name2 have to be adjusted accordingly
for (size_t i1 = 0; i1 <= n1; ++i1)
{
for (size_t i2 = 0; i2 <= n2; ++i2)
{
size_t x = 0;
if (min(i1, i2) == 0) // base case
dp[i1 % 3][i2] = max(i1, i2);
x = max(i1, i2);
else
{
dp[i1 % 3][i2] = min(dp[(i1-1) % 3][i2] + 1, dp[i1 % 3][i2-1] + 1); // deletion and insertion
if (_str1[i1-1] == _str2[i2-1]) // same chars, can skip
dp[i1 % 3][i2] = min(dp[i1 % 3][i2], dp[(i1-1) % 3][i2-1]);
else // different chars so try substitution
dp[i1 % 3][i2] = min(dp[i1 % 3][i2], dp[(i1-1) % 3][i2-1] + 1);
size_t left = dp[(i1-1) % 3][i2];
size_t up = dp[i1 % 3][i2-1];
size_t upleft = dp[(i1 - 1) % 3][i2-1];
// deletion and insertion
x = min(left + 1, up + 1);
if (_str1[i1-1] == _str2[i2-1])
// same chars, can skip
x = min(x, upleft);
else
// different chars so try substitution
x = min(x, upleft + 1);
if (i1 > 1 && i2 > 1 && _str1[i1-1] == _str2[i2-2] && _str1[i1-2] == _str2[i2-1]) // Try transposing
dp[i1 % 3][i2] = min(dp[i1 % 3][i2], dp[(i1-2) % 3][i2-2] + 1);
}
// transposing
if (i1 > 1 && i2 > 1 && _str1[i1 - 1] == _str2[i2 - 2] && _str1[i1 - 2] == _str2[i2 - 1])
x = min(x, dp[(i1 - 2) % 3][i2 - 2] + 1);
}
dp[i1 % 3][i2] = x;
}
return dp[n1 % 3][n2];