Day11 (#123)

* Add @imkaka as a contributor

* day4

* day11

Author: imkaka

day11/C++/longestCommonSubstring.cpp

@@ -0,0 +1,67 @@
+/*
+* @author : imkaka
+* @date   : 04/01/2019
+*/
+
+#include<iostream>
+#include<string>
+
+using namespace std;
+
+void longestCommonSubstrig(string, string);
+
+int main(){
+
+    string str1 = "bisect", str2 = "secret";
+    longestCommonSubstrig(str1, str2); // sec
+    longestCommonSubstrig("abcxyzey", "cxyazeal"); //cxy
+    return 0;
+}
+
+void longestCommonSubstrig(string str1, string str2){
+
+    int m = str1.size();
+    int n = str2.size();
+
+    int LCW[m+1][n+1];
+
+    //Track Len and location.
+    int maxLCW = 0;
+    int loc = m+1;
+
+    for(int i = 0; i <= m; ++i){
+        LCW[i][n] = 0;
+    }
+
+    for(int i = 0; i <= n; ++i){
+        LCW[m][i] = 0;
+    }
+
+    // Calculating the max length of common subword
+    for(int c = n-1; c >= 0; --c){
+        for(int r = m-1; r >= 0; --r){
+            if(str1[r] == str2[c]){
+                LCW[r][c]  = 1 + LCW[r+1][c+1];
+            }
+
+            else{
+                LCW[r][c] = 0;
+            }
+
+            if(LCW[r][c] > maxLCW){
+
+                maxLCW = LCW[r][c];
+                loc = r;
+            }
+        }
+    }
+
+// Finding the Common SubWord
+    string re = "";
+    for(int r = loc; r < loc + maxLCW; ++r){
+        re += char(str1[r]);
+    }
+
+    cout << re << endl;
+
+}

day11/README.md

@@ -80,7 +80,7 @@ function longestSubstring (str1, str2) {
             break;
         }
     }
-    
+
     // Return the reverse of maxSubStr
     return maxSubStr.split('').reverse().join('');
 }
@@ -114,7 +114,7 @@ int main() {
   int lcs[n + 1][m + 1];
 
   int ma = 0;
-  int mi = 0; 
+  int mi = 0;
   int mj = 0;
   for(int i =0; i <=n; i++){
     for(int j = 0; j <=m;j++){
@@ -126,7 +126,7 @@ int main() {
            mj = j;
            ma = lcs[i][j];
         }
-       
+
       }
       else{
         lcs[i][j]= 0;
@@ -144,10 +144,84 @@ int main() {
         }
     }
     reverse(ans.begin(), ans.end());
-  cout << "len : " << ma << " is " << ans;   
+  cout << "len : " << ma << " is " << ans;
 }
 ```
 
+### [Solution by @imkaka](./C++/longetCommonSubstring.cpp)
+
+```cpp
+
+/*
+* @author : imkaka
+* @date   : 04/01/2019
+*/
+
+#include<iostream>
+#include<string>
+
+using namespace std;
+
+void longestCommonSubstrig(string, string);
+
+int main(){
+
+    string str1 = "bisect", str2 = "secret";
+    longestCommonSubstrig(str1, str2); // sec
+    longestCommonSubstrig("abcxyzey", "cxyazeal"); //cxy
+    return 0;
+}
+
+void longestCommonSubstrig(string str1, string str2){
+
+    int m = str1.size();
+    int n = str2.size();
+
+    int LCW[m+1][n+1];
+
+    //Track Len and location.
+    int maxLCW = 0;
+    int loc = m+1;
+
+    for(int i = 0; i <= m; ++i){
+        LCW[i][n] = 0;
+    }
+
+    for(int i = 0; i <= n; ++i){
+        LCW[m][i] = 0;
+    }
+
+    // Calculating the max length of common subword
+    for(int c = n-1; c >= 0; --c){
+        for(int r = m-1; r >= 0; --r){
+            if(str1[r] == str2[c]){
+                LCW[r][c]  = 1 + LCW[r+1][c+1];
+            }
+
+            else{
+                LCW[r][c] = 0;
+            }
+
+            if(LCW[r][c] > maxLCW){
+
+                maxLCW = LCW[r][c];
+                loc = r;
+            }
+        }
+    }
+
+// Finding the Common SubWord
+    string re = "";
+    for(int r = loc; r < loc + maxLCW; ++r){
+        re += char(str1[r]);
+    }
+
+    cout << re << endl;
+
+}
+
+```
+
 ## Java Implementation
 
 ### [Solution](./Java/longestCommonSubstring.java)