2022-08-12

[Zheaoli]

2022-08-12

[SaraadKun]

1282. 用户分组

class Solution {
    public List<List<Integer>> groupThePeople(int[] groupSizes) {
        int n = groupSizes.length;
        List<List<Integer>> ans = new ArrayList<>();
        //key为groupSizes[i],value为i集合,当value.size() == key时加入结果集
        Map<Integer, List<Integer>> map = new HashMap<>();
        for (int i = 0; i < n; i++) {
            List<Integer> cur = map.getOrDefault(groupSizes[i], new ArrayList<>());
            cur.add(i);
            if (cur.size() == groupSizes[i]) {
                ans.add(cur);
                cur = new ArrayList<>(); 
            }
            map.put(groupSizes[i], cur);
        }
        return ans;
    }

---

WeChat: Saraad

[dreamhunter2333]

#include <iostream>
#include <vector>
#include <unordered_map>
using namespace std;
/*
 * @lc app=leetcode.cn id=1282 lang=cpp
 *
 * [1282] 用户分组
 */

// @lc code=start
class Solution
{
public:
    vector<vector<int>> groupThePeople(vector<int> &groupSizes)
    {
        unordered_map<int, vector<int>> cache;
        for (size_t i = 0; i < groupSizes.size(); i++)
        {
            cache[groupSizes[i]].push_back(i);
        }
        vector<vector<int>> res;
        for (auto &&c : cache)
        {
            int count = c.second.size() / c.first;
            for (size_t i = 0; i < count; i++)
            {
                vector<int> group;
                for (size_t j = 0; j < c.first; j++)
                {
                    group.push_back(c.second[i * c.first + j]);
                }
                res.push_back(group);
            }
        }
        return res;
    }
};
// @lc code=end

---

微信id: 而我撑伞 来自 vscode 插件

[gongpeione]

/*
 * @lc app=leetcode id=234 lang=typescript
 *
 * [234] Palindrome Linked List
 */

// @lc code=start
/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */
// type ListNode = {
//     val: number;
//     next: ListNode | null
// };
function isPalindrome(head: ListNode | null): boolean {
    // put all linked list's value to a array
    // const arr = [] as number[];
    // let p = head;
    // while(p) {
    //     arr.push(p.val);
    //     p = p.next;
    // }

    // let r = arr.length - 1;
    // for (let l = 0; l < arr.length; l++) {
    //     if (arr[r] !== arr[l]){
    //         return false;
    //     }
    //     r--;
    // }

    // return true;

    // create two pointer: slow and fast
    // fast pointer moves two steps a time
    // slow pointer moves one step a time
    // at the end of loop, slow pointer would point to the middle of the linked list
    // while the fast pointer point to the last element of the linked list
    let slow = head;
    let fast = head;
    while(fast?.next) {
        fast = fast.next.next;
        slow = slow.next;
    }

    // reverse the second half of the linked list
    // at the end of the loop, slow pointer would point to the last element of the linked list
    let prev: any = null;
    while(slow) {
        const tmp = slow.next;
        slow.next = prev;
        prev = slow;
        slow = tmp;
    }

    let left = head;
    let right = prev;
    while(right) {
        if (right.val !== left.val) {
            return false;
        }
        right = right.next;
        left = left.next;
    }

    return true;
};
// @lc code=end

---

微信id: 弘树 来自 vscode 插件