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yanglbme
2019-08-21 10:10:08 +08:00
parent abc0d365de
commit 69ddc9fc52
101 changed files with 3154 additions and 2984 deletions
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73
Dynamic Programming/Edit Distance.cpp
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@@ -15,8 +15,9 @@
#include <string>
using namespace std;
int min(int x, int y, int z){
return min(min(x,y), z);
int min(int x, int y, int z)
{
return min(min(x, y), z);
}
/* A Naive recursive C++ program to find
@@ -24,62 +25,68 @@ int min(int x, int y, int z){
* str1 to str2.
* O(3^m)
*/
int editDist(string str1, string str2, int m, int n) {
if(m == 0) return n;
if(n == 0) return m;
//If last characters are same then continue
//for the rest of them.
if(str1[m-1] == str2[n-1])
return editDist(str1, str2, m-1, n-1);
int editDist(string str1, string str2, int m, int n)
{
if (m == 0)
return n;
if (n == 0)
return m;
//If last not same, then 3 possibilities
//a.Insert b.Remove c. Replace
//Get min of three and continue for rest.
return 1 + min ( editDist(str1, str2, m, n-1),
editDist(str1, str2, m-1, n),
editDist(str1, str2, m-1, n-1)
);
//If last characters are same then continue
//for the rest of them.
if (str1[m - 1] == str2[n - 1])
return editDist(str1, str2, m - 1, n - 1);
//If last not same, then 3 possibilities
//a.Insert b.Remove c. Replace
//Get min of three and continue for rest.
return 1 + min(editDist(str1, str2, m, n - 1),
editDist(str1, str2, m - 1, n),
editDist(str1, str2, m - 1, n - 1));
}
/* A DP based program
* O(m x n)
*/
int editDistDP(string str1, string str2, int m, int n) {
int editDistDP(string str1, string str2, int m, int n)
{
//Create Table for SubProblems
int dp[m+1][n+1];
int dp[m + 1][n + 1];
//Fill d[][] in bottom up manner
for(int i=0; i<=m; i++) {
for(int j=0; j<=n; j++) {
for (int i = 0; i <= m; i++)
{
for (int j = 0; j <= n; j++)
{
//If str1 empty. Then add all of str2
if(i==0)
if (i == 0)
dp[i][j] = j;
//If str2 empty. Then add all of str1
else if(j==0)
//If str2 empty. Then add all of str1
else if (j == 0)
dp[i][j] = i;
//If character same. Recur for remaining
else if(str1[i-1] == str2[j-1])
dp[i][j] = dp[i-1][j-1];
//If character same. Recur for remaining
else if (str1[i - 1] == str2[j - 1])
dp[i][j] = dp[i - 1][j - 1];
else
dp[i][j] = 1 + min(dp[i][j-1],//Insert
dp[i-1][j],//Remove
dp[i-1][j-1]//Replace
);
dp[i][j] = 1 + min(dp[i][j - 1], //Insert
dp[i - 1][j], //Remove
dp[i - 1][j - 1] //Replace
);
}
}
return dp[m][n];
}
int main() {
int main()
{
string str1 = "sunday";
string str2 = "saturday";
cout << editDist(str1, str2, str1.length(), str2.length()) << endl;
cout << editDistDP(str1, str2, str1.length(), str2.length()) << endl;