【当前无排名】挑战leetcode进入前1w名

李恒道

https://leetcode.cn/problems/number-of-provinces/submissions/574572111/
一眼并查集
但是读错题意了...

class UnionFind {
    //用来解决不同节点间是否拥有相同根的问题
    constructor(n) {
        this.parent = [] //并查集
        this.size = [] //每个节点下拥有的总节点数目
        this.count = 0
        this.init(n)
    }
    //初始化一个并查集
    init(n) {
        this.parent.length = 0
        for (let i = 0; i < n; i++) {
            this.parent[i] = i
        }
        this.count = n
        this.size = new Array(n).fill(1)
    }
    // 在并查集中找到节点node的根节点
    find(node) {
        while (node != this.parent[node]) {
            // 路径压缩，每次查找时都将子节点的父节点设置为父节点的父节点。这样能够不停的扁平化查询树。
            this.parent[node] = this.parent[this.parent[node]]
            node = this.parent[node]
        }
        return node
    }
    //判断两个节点的根节点是不是同一个
    same(left, right) {
        return this.find(left) == this.find(right)
    }
    // 将两个节点关联起来,即两个节点共有一个根节点.和并是将两个节点的根节点合并起来
    union(left, right) {
        let l = this.find(left)
        let r = this.find(right)
        if (l != r) {
            // 左边较小，因此将左边合并到右边的树上
            if (this.size[l] < this.size[r]) {
                this.parent[l] = r
                this.size[r] += this.size[l]
            } else {
                this.parent[r] = l
                this.size[l] += this.size[r]
            }
            // 连通分量减1
            this.count--
            return true
        }
        return false
    }
    //获取总共分了多少组
    getCount() {
        return this.count
    }
}

var findCircleNum = function (isConnected) {
    const union = new UnionFind(isConnected.length);
    for (let index = 0; index < isConnected.length; index++) {
        for (let indey = 0; indey < isConnected[0].length; indey++) {
            if (isConnected[index][indey] == 1) {
                union.union(index, indey)
            }
        }

    }
    return union.getCount()
};```

李恒道

https://leetcode.cn/problems/valid-anagram/submissions/574588789/?envType=study-plan-v2&envId=programming-skills
简单题
打完收工

func isAnagram(s string, t string) bool {
    if len(s) != len(t) {
        return false
    }
    var cache = make(map[int32]int32, 0)
    for _, v := range s {
        cache[v] = cache[v] + 1
    }
    for _, v := range t {
        cache[v] = cache[v] - 1
        if cache[v] < 0 {
            return false
        }
    }
    return true
}

李恒道

https://leetcode.cn/problems/count-pairs-that-form-a-complete-day-i/submissions/574677238/
简单题

var countCompleteDayPairs = function (hours) {
  const cache = new Map();
  let result = 0;
  for (let index = 0; index < hours.length; index++) {
    const hour = hours[index] % 24;
    const target=hour==0?0:24 - hour
    if (cache.has(target)) {
      result += cache.get(target);
    }
    cache.set(hour, (cache.get(hour) ?? 0) + 1);
  }
  return result
};

李恒道

https://leetcode.cn/problems/count-pairs-that-form-a-complete-day-ii/description/
同样的题
秒了

var countCompleteDayPairs = function (hours) {
  const cache = new Map();
  let result = 0;
  for (let index = 0; index < hours.length; index++) {
    const hour = hours[index] % 24;
    const target=hour==0?0:24 - hour
    if (cache.has(target)) {
      result += cache.get(target);
    }
    cache.set(hour, (cache.get(hour) ?? 0) + 1);
  }
  return result
};```

李恒道

https://leetcode.cn/problems/add-binary/submissions/574803015/?envType=study-plan-v2&envId=top-interview-150
简单题
秒了

var addBinary = function (a, b) {
  a = a
    .split("")
    .reverse()
    .map((i) => parseInt(i));
  b = b
    .split("")
    .reverse()
    .map((i) => parseInt(i));
  let extra = 0;
  let len = Math.max(a.length, b.length);
  let result = "";
  for (let index = 0; index < len; index++) {
    const bit1 = a[index];
    const bit2 = b[index];
    const newBit = (bit1 ?? 0) + (bit2 ?? 0) + extra;
    result = (newBit % 2) + result;
    extra = Math.floor(newBit / 2);
  }
  if(extra!==0){
    result = extra + result;
  }
  return result;
};

李恒道

https://leetcode.cn/problems/single-number-iii/submissions/574807196/
这题没想出来
答案真巧妙

var singleNumber = function (nums) {
  let total = 0;
  for (const num of nums) {
    total ^= num;
  }
  const bit = total & -total;
  const ret = [0, 0];
  for (const num of nums) {
    ret[(num & bit) !== 0 ? 1 : 0] ^= num;
  }
  return ret;
};

李恒道

https://leetcode.cn/problems/interleaving-string/submissions/574814157/?envType=study-plan-v2&envId=top-interview-150
dfs过99%....

var isInterleave = function (s1, s2, s3) {
  const cache = new Map();
  const dfs = (p1, p2, p3) => {
    if (p1 == s1.length && p2 == s2.length && p3 == s3.length) {
      return true;
    }
    const flag = `${p1} ${p2} ${p3}`;
    if (cache.has(flag)) {
      return cache.get(flag);
    }

    if (s1[p1] == s3[p3] && s1[p1] !== undefined) {
      //可能是
      let result = dfs(p1 + 1, p2, p3 + 1);
      if (result == true) {
        cache.set(flag, true);
        return true;
      }
    }
    if (s2[p2] == s3[p3] && s2[p2] !== undefined) {
      //可能是
      let result = dfs(p1, p2 + 1, p3 + 1);
      if (result == true) {
        cache.set(flag, true);
        return true;
      }
    }
    cache.set(flag, false);
    return false;
  };
  return dfs(0, 0, 0);
};

王一之

李恒道 发表于 2024-10-22 16:27
[md]https://leetcode.cn/problems/interleaving-string/submissions/574814157/?envType=study-plan-v2&en ...

多少名了

李恒道

王一之 发表于 2024-10-22 17:16
多少名了

还没排名...
今天刚好250题

李恒道

王一之 发表于 2024-10-22 17:16
多少名了

说实话逐渐开始感觉有点到瓶颈了
很多题都是知道解法就起手式秒
不知道怎么扣都抠不出来
完全不是让练习的
单点突破问题全tm背板