Merge pull request #65 from varun514/master

Added KMP Algorithm

Author: probot-auto-merge[bot]

Backtracking/N-Queen/C++/N-Queen.cpp

@@ -0,0 +1,63 @@
+#include<iostream>
+
+using namespace std;
+#define N 5
+
+void printBoard(int board[N][N]){
+    for(int i=0;i<N;i++){
+        for(int j=0;j<N;j++)
+            cout<<board[i][j]<<" ";
+        cout<<endl;
+    }
+}
+
+bool isValid(int board[N][N], int row, int col){
+    for(int i=0;i<col;i++)
+        if(board[row][i])
+            return false;
+
+    for(int i=row,j=col;i>=0 && j>=0;i--,j--)
+        if(board[i][j])
+            return false;
+    
+    for(int i=row,j=col;j>=0 && i<N;i++,j--)
+        if(board[i][j])
+            return false;
+    
+    return true;
+}
+
+bool solveNQueen(int board[N][N], int col){
+    if(col>=N)
+        return true;
+    
+    for(int i=0;i<N;i++){
+        if(isValid(board, i, col)){
+            board[i][col] = 1;
+            if(solveNQueen(board,col+1))
+                return true;
+
+            board[i][col] = 0;
+        }
+    }
+    return false;
+}
+
+bool checkSolution(){
+    int board[N][N];
+    for(int i=0;i<N;i++)
+        for(int j=0;j<N;j++)
+            board[i][j] = 0;
+
+    if(!solveNQueen(board,0)){
+        cout<<"Solution does not exist"<<endl;
+        return false;
+    }
+
+    printBoard(board);
+    return true;
+}
+
+int main(){
+    checkSolution();
+}

KMP/C++/kmp.cpp

@@ -0,0 +1,54 @@
+//Knuth-Patt-Morris Algorithm for pattern searching in given string
+
+
+/*
+    txt is text and pat is the pattern to be searched
+    vector pos stores the end position where pattern is found
+    (0-based indexing)
+    Time Conmplexity: O(pat.length + txt.length)
+        */
+ 
+#include <bits/stdc++.h>
+using namespace std;      
+        
+vector<int> kmp(string txt, string pat) 
+{
+	string s = pat + '$' + txt;
+	int n = s.length(), l = pat.length();
+	vector<int> LPS(n, 0);
+	int k = 0;
+
+	/* Building LPS Array */
+	for(int i = 1; i < n; ++i)
+	{
+		while(k > 0 && s[i] != s[k])
+		{
+			k = LPS[k-1];
+		}
+		if (s[i] == s[k]) 
+		    ++k;
+		LPS[i] = k;
+	}
+	/* Searching for pattern and storing occurences in vector i.e the index where pattern ends */
+	vector<int> pos;
+	for(int i = 0; i < n; ++i)
+	{
+		if (LPS[i] == l)
+		{
+			pos.push_back(i-l-1);
+		}
+	}
+	return pos;
+}
+
+int main()
+{
+	string text,pattern;
+	cin>>text>>pattern;
+	vector<int> ans=kmp(text,pattern);
+	for(auto y:ans)
+	{
+		cout<<y+1<<endl;
+	}
+	return 0;
+}