Add Day 17 Python Implementation (#167)

* Add @aaditkamat as a contributor

* Add Ruby code for Day 1: FizzBuzz problem

* Add Ruby code for Day 2: String reverse problem

* Update README.md for Day 2

* Modify Ruby code and README

* Add condition for nil and wrong type edge cases

* Add a seperate Ruby source code file for palindrome

* Modify code for reverse.rb

* Add seperate palindrome and reverse code sections in README

* Update gitignore

* Refactor palindrome.rb and rename heading in README

* Add solution for Day 3: Hamming Problem

* Add condition for strings of unequal lengths

* Update README

* Change project name and owner in.all-contributorsrc

* Remove merge conflict lines

* Add @shivank86 as a contributor

* Add C++ files for different patterns

* Add author and date comments at the top of C++ files

* Update README.md

* Add solution for Day 6 Problem in Python

* Update README

* Refactor code files

* Modify string representation of output in python files

* Add Ruby solutions for Day 6 problem

* Update README for Ruby code

* Add first version of solutions for Day 7 problem in C++, Java & Ruby

* Modify solutions

* Update Day 7 README

* Remove merge conflicts from CONTRIBUTORS.md

* Add back removed lines in CONTRIBUTORS.md

* Add code sections contributed by @imkaka to day 6 README

* Update README.md

* Add C++ solution

* Add Day 8 solution in C++

* Add Day 8 solution in Java

* Add Day 8 solution in Ruby

* Add Day 8 solution in Python

* Add credits at the top of the code

* Update README

* Update C++ implementation

* Update Python implementation

* Add solution for Day 10: String Permutation Problem in Python

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

* Update Day 10 README

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

* Change heading in README and remove empty directory in day 9

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

* Update README.md

* Add Ruby solutions for Day 13

* Update README

* Add credits to the code

* Add Python solution for Day 13

* Update Day 13 README

* Update fibonacci.py

* Modify Fibonacci python code section in day 13 README

* Add Ruby solution to Day 16 problem

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

* Update Day 16 README with Ruby implementation

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

* Change wording of print statement

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

* Add Python solution to Day 17 problem

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

* Add Python implementation to Day 17 README

Signed-off-by: Aadit Rahul Kamat <aadit.k12@gmail.com>

day17/Python/n_queens.py

@@ -0,0 +1,80 @@
+"""
+@author:aaditkamat
+@date: 13/01/2019
+"""
+def print_chessboard(chessboard):
+    for i in range(len(chessboard)):
+        print(chessboard[i])
+
+def fill_chessboard(i, j,chessboard):
+    chessboard[i][j] = 1
+
+    for x in range(len(chessboard)):
+        if x != i:
+            chessboard[x][j] = 0
+
+    for y in range(len(chessboard)):
+        if y != j:
+            chessboard[i][y] = 0
+
+    x, y = (i + 1, j + 1)
+    while x < len(chessboard) and y < len(chessboard):
+        chessboard[x][y] = 0
+        x += 1
+        y += 1
+
+    x, y = (i - 1, j - 1)
+    while x >= 0 and y >= 0:
+        chessboard[x][y] = 0
+        x -= 1
+        y -= 1
+
+    x, y = (i + 1, j - 1)
+    while x < len(chessboard) and y >= 0:
+        chessboard[x][y] = 0
+        x += 1
+        y -= 1
+
+    x, y = (i - 1, j + 1)
+    while x >= 0 and y < len(chessboard):
+        chessboard[x][y] = 0
+        x -= 1
+        y += 1
+
+def try_position(i, chessboard):
+    fill_chessboard(0, i, chessboard)
+
+    for i in range(1, len(chessboard)):
+        for j in range(len(chessboard)):
+            if chessboard[i][j] == -1:
+                fill_chessboard(i, j, chessboard)
+
+def reset_chessboard(chessboard):
+    for i in range(len(chessboard)):
+        for j in range(len(chessboard)):
+            chessboard[i][j] = -1
+
+def is_correct(chessboard):
+    for i in range(len(chessboard)):
+        if chessboard[i].count(1) == 0:
+            return False
+    return True
+
+def n_queens(num):
+    chessboard = []
+    for i in range(num):
+        chessboard.append([-1] * num)
+
+    for i in range(num):
+        try_position(i, chessboard)
+        if (is_correct(chessboard)):
+            print_chessboard(chessboard)
+            return
+        reset_chessboard(chessboard)
+
+def main():
+    print("Enter number of queens: ", end="")
+    num = int(input())
+    n_queens(num)
+
+main()

day17/README.md

@@ -210,6 +210,93 @@ int main() {
 }
 ```
 
+## Python Implemetation
+
+### [Solution](./Python/n_queens.py)
+
+```python
+"""
+@author:aaditkamat
+@date: 13/01/2019
+"""
+def print_chessboard(chessboard):
+    for i in range(len(chessboard)):
+        print(chessboard[i])
+
+def fill_chessboard(i, j,chessboard):
+    chessboard[i][j] = 1
+
+    for x in range(len(chessboard)):
+        if x != i:
+            chessboard[x][j] = 0
+
+    for y in range(len(chessboard)):
+        if y != j:
+            chessboard[i][y] = 0
+
+    x, y = (i + 1, j + 1)
+    while x < len(chessboard) and y < len(chessboard):
+        chessboard[x][y] = 0
+        x += 1
+        y += 1
+
+    x, y = (i - 1, j - 1)
+    while x >= 0 and y >= 0:
+        chessboard[x][y] = 0
+        x -= 1
+        y -= 1
+
+    x, y = (i + 1, j - 1)
+    while x < len(chessboard) and y >= 0:
+        chessboard[x][y] = 0
+        x += 1
+        y -= 1
+
+    x, y = (i - 1, j + 1)
+    while x >= 0 and y < len(chessboard):
+        chessboard[x][y] = 0
+        x -= 1
+        y += 1
+
+def try_position(i, chessboard):
+    fill_chessboard(0, i, chessboard)
+
+    for i in range(1, len(chessboard)):
+        for j in range(len(chessboard)):
+            if chessboard[i][j] == -1:
+                fill_chessboard(i, j, chessboard)
+
+def reset_chessboard(chessboard):
+    for i in range(len(chessboard)):
+        for j in range(len(chessboard)):
+            chessboard[i][j] = -1
+
+def is_correct(chessboard):
+    for i in range(len(chessboard)):
+        if chessboard[i].count(1) == 0:
+            return False
+    return True
+
+def n_queens(num):
+    chessboard = []
+    for i in range(num):
+        chessboard.append([-1] * num)
+
+    for i in range(num):
+        try_position(i, chessboard)
+        if (is_correct(chessboard)):
+            print_chessboard(chessboard)
+            return
+        reset_chessboard(chessboard)
+
+def main():
+    print("Enter number of queens: ", end="")
+    num = int(input())
+    n_queens(num)
+
+main()
+```
+
 ## Java Implementation
 
 ### [Solution](./Java/nQueen.java)