translation: Add Python and Java code for EN version (#1345)

* Add the intial translation of code of all the languages

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* Add Python and Java code for EN version

en/codes/python/chapter_heap/heap.py

@@ -0,0 +1,71 @@
+"""
+File: heap.py
+Created Time: 2023-02-23
+Author: krahets (krahets@163.com)
+"""
+
+import sys
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).parent.parent))
+from modules import print_heap
+
+import heapq
+
+
+def test_push(heap: list, val: int, flag: int = 1):
+    heapq.heappush(heap, flag * val)  # Push the element into heap
+    print(f"\nElement {val} after pushed into heap")
+    print_heap([flag * val for val in heap])
+
+
+def test_pop(heap: list, flag: int = 1):
+    val = flag * heapq.heappop(heap)  # Pop the element at the heap top
+    print(f"\nHeap top element {val} after exiting heap")
+    print_heap([flag * val for val in heap])
+
+
+"""Driver Code"""
+if __name__ == "__main__":
+    # Initialize min-heap
+    min_heap, flag = [], 1
+    # Initialize max-heap
+    max_heap, flag = [], -1
+
+    print("\nThe following test case is for max-heap")
+    # Python's heapq module implements min-heap by default
+    # Consider "negating the elements" before entering the heap, thus reversing the comparator to implement a max-heap
+    # In this example, flag = 1 corresponds to min-heap, flag = -1 corresponds to max-heap
+
+    # Push the element into heap
+    test_push(max_heap, 1, flag)
+    test_push(max_heap, 3, flag)
+    test_push(max_heap, 2, flag)
+    test_push(max_heap, 5, flag)
+    test_push(max_heap, 4, flag)
+
+    # Access heap top element
+    peek: int = flag * max_heap[0]
+    print(f"\nHeap top element is {peek}")
+
+    # Pop the element at the heap top
+    test_pop(max_heap, flag)
+    test_pop(max_heap, flag)
+    test_pop(max_heap, flag)
+    test_pop(max_heap, flag)
+    test_pop(max_heap, flag)
+
+    # Get heap size
+    size: int = len(max_heap)
+    print(f"\nNumber of heap elements is {size}")
+
+    # Determine if heap is empty
+    is_empty: bool = not max_heap
+    print(f"\nIs the heap empty {is_empty}")
+
+    # Enter list and build heap
+    # Time complexity is O(n), not O(nlogn)
+    min_heap = [1, 3, 2, 5, 4]
+    heapq.heapify(min_heap)
+    print("\nEnter list and build min-heap")
+    print_heap(min_heap)

en/codes/python/chapter_heap/my_heap.py

@@ -0,0 +1,137 @@
+"""
+File: my_heap.py
+Created Time: 2023-02-23
+Author: krahets (krahets@163.com)
+"""
+
+import sys
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).parent.parent))
+from modules import print_heap
+
+
+class MaxHeap:
+    """Max-heap"""
+
+    def __init__(self, nums: list[int]):
+        """Constructor, build heap based on input list"""
+        # Add all list elements into the heap
+        self.max_heap = nums
+        # Heapify all nodes except leaves
+        for i in range(self.parent(self.size() - 1), -1, -1):
+            self.sift_down(i)
+
+    def left(self, i: int) -> int:
+        """Get index of left child node"""
+        return 2 * i + 1
+
+    def right(self, i: int) -> int:
+        """Get index of right child node"""
+        return 2 * i + 2
+
+    def parent(self, i: int) -> int:
+        """Get index of parent node"""
+        return (i - 1) // 2  # Integer division down
+
+    def swap(self, i: int, j: int):
+        """Swap elements"""
+        self.max_heap[i], self.max_heap[j] = self.max_heap[j], self.max_heap[i]
+
+    def size(self) -> int:
+        """Get heap size"""
+        return len(self.max_heap)
+
+    def is_empty(self) -> bool:
+        """Determine if heap is empty"""
+        return self.size() == 0
+
+    def peek(self) -> int:
+        """Access heap top element"""
+        return self.max_heap[0]
+
+    def push(self, val: int):
+        """Push the element into heap"""
+        # Add node
+        self.max_heap.append(val)
+        # Heapify from bottom to top
+        self.sift_up(self.size() - 1)
+
+    def sift_up(self, i: int):
+        """Start heapifying node i, from bottom to top"""
+        while True:
+            # Get parent node of node i
+            p = self.parent(i)
+            # When "crossing the root node" or "node does not need repair", end heapification
+            if p < 0 or self.max_heap[i] <= self.max_heap[p]:
+                break
+            # Swap two nodes
+            self.swap(i, p)
+            # Loop upwards heapification
+            i = p
+
+    def pop(self) -> int:
+        """Element exits heap"""
+        # Empty handling
+        if self.is_empty():
+            raise IndexError("Heap is empty")
+        # Swap the root node with the rightmost leaf node (swap the first element with the last element)
+        self.swap(0, self.size() - 1)
+        # Remove node
+        val = self.max_heap.pop()
+        # Heapify from top to bottom
+        self.sift_down(0)
+        # Return heap top element
+        return val
+
+    def sift_down(self, i: int):
+        """Start heapifying node i, from top to bottom"""
+        while True:
+            # Determine the largest node among i, l, r, noted as ma
+            l, r, ma = self.left(i), self.right(i), i
+            if l < self.size() and self.max_heap[l] > self.max_heap[ma]:
+                ma = l
+            if r < self.size() and self.max_heap[r] > self.max_heap[ma]:
+                ma = r
+            # If node i is the largest or indices l, r are out of bounds, no further heapification needed, break
+            if ma == i:
+                break
+            # Swap two nodes
+            self.swap(i, ma)
+            # Loop downwards heapification
+            i = ma
+
+    def print(self):
+        """Print heap (binary tree)"""
+        print_heap(self.max_heap)
+
+
+"""Driver Code"""
+if __name__ == "__main__":
+    # Initialize max-heap
+    max_heap = MaxHeap([9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2])
+    print("\nEnter list and build heap")
+    max_heap.print()
+
+    # Access heap top element
+    peek = max_heap.peek()
+    print(f"\nHeap top element is {peek}")
+
+    # Push the element into heap
+    val = 7
+    max_heap.push(val)
+    print(f"\nElement {val} after pushed into heap")
+    max_heap.print()
+
+    # Pop the element at the heap top
+    peek = max_heap.pop()
+    print(f"\nHeap top element {peek} after exiting heap")
+    max_heap.print()
+
+    # Get heap size
+    size = max_heap.size()
+    print(f"\nNumber of heap elements is {size}")
+
+    # Determine if heap is empty
+    is_empty = max_heap.is_empty()
+    print(f"\nIs the heap empty {is_empty}")

en/codes/python/chapter_heap/top_k.py

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+"""
+File: top_k.py
+Created Time: 2023-06-10
+Author: krahets (krahets@163.com)
+"""
+
+import sys
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).parent.parent))
+from modules import print_heap
+
+import heapq
+
+
+def top_k_heap(nums: list[int], k: int) -> list[int]:
+    """Using heap to find the largest k elements in an array"""
+    # Initialize min-heap
+    heap = []
+    # Enter the first k elements of the array into the heap
+    for i in range(k):
+        heapq.heappush(heap, nums[i])
+    # From the k+1th element, keep the heap length as k
+    for i in range(k, len(nums)):
+        # If the current element is larger than the heap top element, remove the heap top element and enter the current element into the heap
+        if nums[i] > heap[0]:
+            heapq.heappop(heap)
+            heapq.heappush(heap, nums[i])
+    return heap
+
+
+"""Driver Code"""
+if __name__ == "__main__":
+    nums = [1, 7, 6, 3, 2]
+    k = 3
+
+    res = top_k_heap(nums, k)
+    print(f"The largest {k} elements are")
+    print_heap(res)