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util.cpp
91 lines (81 loc) · 2.56 KB
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util.cpp
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#include "util.h"
Util::Util()
{
}
int Util::levensteinDistance(const QString &s1, const QString &s2)
{
int s1len = s1.size();
int s2len = s2.size();
auto column_start = (decltype(s1len))1;
auto column = new decltype(s1len)[s1len + 1];
std::iota(column + column_start, column + s1len + 1, column_start);
for (auto x = column_start; x <= s2len; x++) {
column[0] = x;
auto last_diagonal = x - column_start;
for (auto y = column_start; y <= s1len; y++) {
auto old_diagonal = column[y];
auto possibilities = {
column[y] + 1,
column[y - 1] + 1,
last_diagonal + (s1[y - 1] == s2[x - 1]? 0 : 1)
};
column[y] = std::min(possibilities);
last_diagonal = old_diagonal;
}
}
auto result = column[s1len];
delete[] column;
return result;
}
QString Util::maxSubstring(const QString &s1, const QString &s2)
{
std::tuple<Matrix,ArrowTable> len= maxSubstringLength(s1,s2);
QString result = maxSubstringRecur(std::get<1>(len),s1,s1.length(),s2.length(),QString(""));
std::reverse(result.begin(),result.end());
return result;
}
std::tuple<Matrix, ArrowTable> Util::maxSubstringLength(const QString &s1, const QString &s2)
{
int m = s1.length()+1;
int n = s2.length()+1;
Matrix c(m);
ArrowTable b(m);
for(int i = 0; i<m;++i){
c[i] = std::vector<int>(n);
b[i] = std::vector<ARROWS>(n);
for(int j=0;j<n;++j){
c[i][j] = 0;
b[i][j] = NO_ARROW;
}
}
for(int i = 1 ;i<m;++i){
for(int j = 1; j<n;++j){
if (s1[i-1]==s2[j-1]){
c[i][j] = c[i-1][j-1] + 1;
b[i][j] = DIAGONAL_ARROW;
} else{
if (c[i-1][j] >= c[i][j-1]){
c[i][j] = c[i-1][j];
b[i][j] = UP_ARROW;
} else {
c[i][j] = c[i][j-1];
b[i][j] = LEFT_ARROW;
}
}
}
}
return std::make_tuple(c,b);
}
QString Util::maxSubstringRecur(const ArrowTable &tbl, const QString &s1, int s1len, int s2len, QString result)
{
if(s1len == 0 || s2len == 0){
return result;
}
if (tbl[s1len][s2len] == DIAGONAL_ARROW){
return maxSubstringRecur(tbl,s1,s1len-1,s2len-1,result + s1[s1len-1]);
}else if (tbl[s1len][s2len] == UP_ARROW){
return maxSubstringRecur(tbl,s1,s1len-1,s2len,result);
} else {
return maxSubstringRecur(tbl,s1,s1len,s2len-1,result);
}
}