11: 1146. Snapshot Array.py

# problem:
# https://leetcode.com/problems/snapshot-array/

# solution:
class SnapshotArray(object):
    def __init__(self, n):
        self.cache = [[[-1, 0]] for _ in range(n)]
        self.i = 0

    def set(self, index, val):
        self.cache[index].append([self.i, val])

    def snap(self):
        self.i += 1
        return self.i - 1

    @lru_cache(maxsize=None)
    def get(self, index, snap_id):
        i = bisect.bisect(self.cache[index], [snap_id + 1]) - 1
        return self.cache[index][i][1]