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edit_distance_cache.cpp
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edit_distance_cache.cpp
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#include <iostream>
#include <string>
#include <map>
using namespace std;
int min(int i, int j, int k)
{
int iMin = i;
if(iMin > j) iMin = j;
if(iMin > k) iMin = k;
return iMin;
}
int inCache(int i, int j, map<int, map<int, int> >& mCache)
{
map<int, map<int, int> >::const_iterator iter = mCache.find(i);
if(iter == mCache.end()) return -1;
const map<int, int>& mTmp = iter->second;
map<int, int>::const_iterator iter1 = mTmp.find(j);
if(iter1 == mTmp.end()) return -2;
return iter1->second;
}
int minDistance(const string& s1, const string& s2, int i, int j, map<int, map<int, int> >& mCache)
{
if(j == -1) return i + 1; //依次删除
if(i == -1) return j + 1; //依次插入
int iRet = inCache(i, j, mCache);
if(iRet > 0)
{
return iRet;
}
if(s1.at(i) == s2.at(j))
{
iRet = minDistance(s1, s2, i - 1, j - 1, mCache); //skip
mCache[i][j] = iRet;
return iRet;
}
int iVar1, iVar2, iVar3;
//插入
iVar1 = minDistance(s1, s2, i, j - 1, mCache) + 1;
//替换
iVar2 = minDistance(s1, s2, i - 1, j - 1, mCache) + 1;
//删除
iVar3 = minDistance(s1, s2, i - 1, j, mCache) + 1;
iRet = min(iVar1, iVar2, iVar3);
mCache[i][j] = iRet;
return iRet;
}
int main()
{
string s1 = "horse";
string s2 = "ros";
map<int, map<int, int> > mCache; // i, j, value
int iRet = minDistance(s1, s2, s1.size() - 1, s2.size() - 1, mCache);
cout << "s1:" << s1 << ",s2:" << s2 << ",result:" << iRet << endl;
mCache.clear(); //这里记得清空
s1 = "intention";
s2 = "execution";
iRet = minDistance(s1, s2, s1.size() - 1, s2.size() - 1, mCache);
cout << "s1:" << s1 << ",s2:" << s2 << ",result:" << iRet << endl;
return 0;
}