added brute force and kmp in python (#129)

* added brute force and kmp in python

* added author comment

Author: prateek3255

day12/Python/KMP.py

@@ -0,0 +1,45 @@
+'''
+  @author prateek3255
+  @date 05/01/2018
+ '''
+ 
+def kmp(string,pattern):
+    n=len(string)
+    m=len(pattern)
+    lps=calculateLPS(pattern)
+    i=0
+    j=0
+    while i<n:
+        if pattern[j]==string[i]:
+            i+=1
+            j+=1
+        if j==m:
+            return i-j
+        elif i<n and pattern[j]!=string[i]:
+            if j!=0:
+                j=lps[j-1]
+            else:
+                i+=1
+    return -1
+
+def calculateLPS(pattern):
+    lps=[0]*len(pattern)
+    i=1
+    lenPat=0
+    while i<len(pattern):
+        if pattern[i]==pattern[lenPat]:
+            lenPat+=1
+            lps[i]=lenPat
+            i+=1
+        else:
+            if lenPat!=0:
+                lenPat=lps[lenPat-1]
+            else:
+                lps[i]=0
+                i+=1
+    return lps
+
+print(kmp("helloworld","hello"))
+print(kmp("helloworld","hop"))
+print(kmp("ABABDABACDABABCABAB","ABABCABAB"))
+

day12/Python/bruteForce.py

@@ -0,0 +1,14 @@
+'''
+  @author prateek3255
+  @date 05/01/2018
+ '''
+
+def subStringSearch(string,pattern):
+    for i in range(len(string)-len(pattern)):
+        if string[i:i+len(pattern)]==pattern:
+            return i
+    return -1
+
+print(subStringSearch("helloworld","hello"))
+print(subStringSearch("helloworld","hop"))
+print(subStringSearch("abcrxyzgf","xyz"))

day12/README.md

@@ -75,6 +75,27 @@ substringSearch ("helloworld", "world");
 substringSearch ("abcrxyzgf", "xyz");
 ```
 
+### Python Implementation
+
+#### [Solution](./Python/bruteForce.py)
+
+```py
+'''
+  @author prateek3255
+  @date 05/01/2018
+ '''
+
+def subStringSearch(string,pattern):
+    for i in range(len(string)-len(pattern)):
+        if string[i:i+len(pattern)]==pattern:
+            return i
+    return -1
+
+print(subStringSearch("helloworld","hello"))
+print(subStringSearch("helloworld","hop"))
+print(subStringSearch("abcrxyzgf","xyz"))
+```
+
 ## B) Knuth-Morris-Pratt Algorithm
 
 ### JavaScript Implementation
@@ -85,6 +106,53 @@ substringSearch ("abcrxyzgf", "xyz");
 To Be Added
 ```
 
+### Python Implementation
+
+#### [Solution](./Pyhton/KMP.py)
+
+```py
+def kmp(string,pattern):
+    n=len(string)
+    m=len(pattern)
+    lps=calculateLPS(pattern)
+    i=0
+    j=0
+    while i<n:
+        if pattern[j]==string[i]:
+            i+=1
+            j+=1
+        if j==m:
+            return i-j
+        elif i<n and pattern[j]!=string[i]:
+            if j!=0:
+                j=lps[j-1]
+            else:
+                i+=1
+    return -1
+
+def calculateLPS(pattern):
+    lps=[0]*len(pattern)
+    i=1
+    lenPat=0
+    while i<len(pattern):
+        if pattern[i]==pattern[lenPat]:
+            lenPat+=1
+            lps[i]=lenPat
+            i+=1
+        else:
+            if lenPat!=0:
+                lenPat=lps[lenPat-1]
+            else:
+                lps[i]=0
+                i+=1
+    return lps
+
+print(kmp("helloworld","hello"))
+print(kmp("helloworld","hop"))
+print(kmp("ABABDABACDABABCABAB","ABABCABAB"))
+```
+
+
 ##  C) Z Algorithm
 
 ### JavaScript Implementation