feat: solve No.1282

Author: BaffinLee

1201-1300/1282. Group the People Given the Group Size They Belong To.md

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+# 1282. Group the People Given the Group Size They Belong To
+
+- Difficulty: Medium.
+- Related Topics: Array, Hash Table.
+- Similar Questions: Maximum Number of Groups With Increasing Length.
+
+## Problem
+
+There are `n` people that are split into some unknown number of groups. Each person is labeled with a **unique ID** from `0` to `n - 1`.
+
+You are given an integer array `groupSizes`, where `groupSizes[i]` is the size of the group that person `i` is in. For example, if `groupSizes[1] = 3`, then person `1` must be in a group of size `3`.
+
+Return **a list of groups such that each person `i` is in a group of size `groupSizes[i]`**.
+
+Each person should appear in **exactly one group**, and every person must be in a group. If there are multiple answers, **return any of them**. It is **guaranteed** that there will be **at least one** valid solution for the given input.
+
+ 
+Example 1:
+
+```
+Input: groupSizes = [3,3,3,3,3,1,3]
+Output: [[5],[0,1,2],[3,4,6]]
+Explanation: 
+The first group is [5]. The size is 1, and groupSizes[5] = 1.
+The second group is [0,1,2]. The size is 3, and groupSizes[0] = groupSizes[1] = groupSizes[2] = 3.
+The third group is [3,4,6]. The size is 3, and groupSizes[3] = groupSizes[4] = groupSizes[6] = 3.
+Other possible solutions are [[2,1,6],[5],[0,4,3]] and [[5],[0,6,2],[4,3,1]].
+```
+
+Example 2:
+
+```
+Input: groupSizes = [2,1,3,3,3,2]
+Output: [[1],[0,5],[2,3,4]]
+```
+
+ 
+**Constraints:**
+
+
+	
+- `groupSizes.length == n`
+	
+- `1 <= n <= 500`
+	
+- `1 <= groupSizes[i] <= n`
+
+
+
+## Solution
+
+```javascript
+/**
+ * @param {number[]} groupSizes
+ * @return {number[][]}
+ */
+var groupThePeople = function(groupSizes) {
+    var map = Array(groupSizes.length + 1).fill(0).map(() => []);
+    var res = [];
+    for (var i = 0; i < groupSizes.length; i++) {
+        var size = groupSizes[i];
+        map[size].push(i);
+        if (map[size].length === size) {
+            res.push(map[size]);
+            map[size] = [];
+        }
+    }
+    return res;
+};
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity : O(n).
+* Space complexity : O(n).