Create 1146-snapshot-array.js

Author: everthis

1146-snapshot-array.js

@@ -0,0 +1,57 @@
+/**
+ * @param {number} length
+ */
+const SnapshotArray = function(length) {
+  this.arr = new Array(length).fill(0);
+  this.snaps = new Array(length);
+  this.count = 0;
+};
+
+/**
+ * @param {number} index
+ * @param {number} val
+ * @return {void}
+ */
+SnapshotArray.prototype.set = function(index, val) {
+  if (this.snaps[index] == undefined) {
+    this.snaps[index] = {};
+  }
+
+  this.snaps[index][this.count] = val;
+};
+
+/**
+ * @return {number}
+ */
+SnapshotArray.prototype.snap = function() {
+  return this.count++;
+};
+
+/**
+ * @param {number} index
+ * @param {number} snap_id
+ * @return {number}
+ */
+SnapshotArray.prototype.get = function(index, snap_id) {
+  if (this.snaps[index] == undefined) return 0;
+
+  let res = 0;
+  while (snap_id >= 0) {
+    if (this.snaps[index][snap_id] == undefined) {
+      snap_id--;
+    } else {
+      res = this.snaps[index][snap_id];
+      snap_id = -1;
+    }
+  }
+
+  return res;
+};
+
+/**
+ * Your SnapshotArray object will be instantiated and called as such:
+ * var obj = new SnapshotArray(length)
+ * obj.set(index,val)
+ * var param_2 = obj.snap()
+ * var param_3 = obj.get(index,snap_id)
+ */