Java Solution for Snapshot Array Problem
Intuition\n Describe your first thoughts on how to solve this problem. \nThe intuition behind this approach is to efficiently store the changes made to the arra
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\nThe intuition behind this approach is to efficiently store the changes made to the array over time and retrieve the correct value based on the provided snap_id. By using TreeMap, we can efficiently retrieve the closest snap_id that is less than or equal to the given snap_id.\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\nThe SnapshotArray class is implemented using a list of TreeMap objects to store snapshots of the array. Each TreeMap represents the snapshots taken for a specific index in the array. The key in the TreeMap represents the snap_id, and the corresponding value represents the value of the element at that index for that particular snap_id.\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\nThe time complexity of the set operation is O(log n), where n is the number of snapshots taken so far. This is because we need to update the TreeMap for the specific index with the new snap_id and value.\n\nThe time complexity of the snap operation is O(1) since we only increment the snap_id.\n\nThe time complexity of the get operation is O(log n) as we need to find the closest snap_id less than or equal to the given snap_id using the floorEntry method of TreeMap.\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\nThe space complexity of the SnapshotArray class is O(n * m), where n is the length of the array and m is the number of snapshots taken so far. We store a TreeMap for each index in the array, and each TreeMap can have a maximum of m entries.\n\n# Code\n```\nimport java.util.ArrayList;\nimport java.util.HashMap;\nimport java.util.List;\nimport java.util.Map;\nimport java.util.TreeMap;\n\nclass SnapshotArray {\n    private int snapId;\n    private List<TreeMap<Integer, Integer>> snapshots;\n\n\n    public SnapshotArray(int length) {\n        snapId = 0;\n        snapshots = new ArrayList<>();\n        for (int i = 0; i < length; i++) \n        {\n            TreeMap<Integer, Integer> map = new TreeMap<>();\n            map.put(0, 0);\n            snapshots.add(map);\n        }\n    }\n    \n    public void set(int index, int val) {\n        TreeMap<Integer, Integer> snapshot = snapshots.get(index);\n        snapshot.put(snapId, val);\n    }\n    \n    public int snap() {\n         return snapId++;\n    }\n    \n    public int get(int index, int snap_id) {\n        TreeMap<Integer, Integer> snapshot = snapshots.get(index);\n        Map.Entry<Integer, Integer> entry = snapshot.floorEntry(snap_id);\n        return entry.getValue();\n    }\n}\n\n/**\n * Your SnapshotArray object will be instantiated and called as such:\n * SnapshotArray obj = new SnapshotArray(length);\n * obj.set(index,val);\n * int param_2 = obj.snap();\n * int param_3 = obj.get(index,snap_id);\n */\n```
['Java']