Algorithms : complete 01-algorithmic_toolbox 04-dynamic_programming

1 files changed, 38 insertions, 3 deletions

diff --git a/01-algorithmic_toolbox/04-dynamic_programming/03-edit_distance/edit_distance.cpp b/01-algorithmic_toolbox/04-dynamic_programming/03-edit_distance/edit_distance.cpp
index fd7d16e..8b124ed 100644
--- a/01-algorithmic_toolbox/04-dynamic_programming/03-edit_distance/edit_distance.cpp
+++ b/01-algorithmic_toolbox/04-dynamic_programming/03-edit_distance/edit_distance.cpp
@@ -3,9 +3,44 @@
 
 using std::string;
 
-int edit_distance(const string &str1, const string &str2) {
-  //write your code here
-  return 0;
+int edit_distance(const string &str1, const string &str2)
+{
+    int s1 = str1.length() + 1;
+    int s2 = str2.length() + 1;
+    int *m = new int[s1 * s2];
+
+    for (int i = 0; i < s1; i++) m[i] = i;
+    for (int i = 0; i < s2; i++) m[i * s1] = i;
+
+    for (int i = 1; i < s2; i++) {
+        for (int j = 1; j < s1; j++) {
+            int insertion = m[i * s1 + j - 1] + 1;
+            int deletion = m[(i - 1 ) * s1 + j] + 1;
+            int match = m[(i - 1) * s1 + j - 1];
+            int mismatch = match + 1;
+            if (str2[i - 1] == str1[j - 1]) {
+                /* m[i, j] = ((insertion < deletion) ? */
+                m[i * s1 + j] = ((insertion < deletion) ?
+                        ((insertion < match) ? insertion : match)
+                        : ((deletion < match) ? deletion : match));
+            }
+            else {
+                m[i * s1 + j] = ((insertion < deletion) ?
+                        ((insertion < mismatch) ? insertion : mismatch)
+                        : ((deletion < mismatch) ? deletion : mismatch));
+            }
+        }
+    }
+
+    /* for (int i = 0; i < s2; i++) { */
+    /*     for (int j = 0; j < s1; j++) */
+    /*         std::cout << m[i * s1 + j] << " "; */
+    /*     std::cout << std::endl; */
+    /* } */
+
+    delete [] m;
+
+    return m[s1 * s2 - 1];
 }
 
 int main() {