# Heap¶

Table of Contents

## Heap Sort¶

```
>>> import heapq
>>> a = [5, 1, 3, 2, 6]
>>> h = []
>>> for x in a:
... heapq.heappush(h, x)
...
>>> x = [heapq.heappop(h) for _ in range(len(a))]
>>> x
[1, 2, 3, 5, 6]
```

## Priority Queue¶

```
import heapq
h = []
heapq.heappush(h, (1, "1")) # (priority, value)
heapq.heappush(h, (5, "5"))
heapq.heappush(h, (3, "3"))
heapq.heappush(h, (2, "2"))
x = [heapq.heappop(h) for _ in range(len(h))]
print(x)
```

```
import heapq
class Num(object):
def __init__(self, n):
self._n = n
def __lt__(self, other):
return self._n < other._n
def __repr__(self):
return self.__str__()
def __str__(self):
return f"Num({self._n})"
h = []
heapq.heappush(h, Num(5))
heapq.heappush(h, Num(2))
heapq.heappush(h, Num(1))
x = [heapq.heappop(h) for _ in range(len(h))]
print(x)
# output: [Num(1), Num(2), Num(5)]
```