第 177 场周赛

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Words count in article: 556 | Reading time ≈ 3

5169. 日期之间隔几天

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class Solution(object):
    def daysBetweenDates(self, date1, date2):
        import datetime
        d1 = datetime.datetime.strptime(date1, '%Y-%m-%d')
        d2 = datetime.datetime.strptime(date2, '%Y-%m-%d')
        if(d1 > d2):
            d = d1 - d2
        else:
            d = d2 - d1
        return d.days

5170. 验证二叉树

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class Solution {
public:
    bool validateBinaryTreeNodes(int n, vector<int>& leftChild, vector<int>& rightChild) {
        vector<int> visited(n);
        queue<int> q;
        q.push(0);
        int count = 0;
        while(!q.empty()){
            int cur = q.front(); q.pop();
            if(visited[cur]) return false;
            visited[cur] = 1;
            if(leftChild[cur] != -1) q.push(leftChild[cur]);
            if(rightChild[cur] != -1) q.push(rightChild[cur]);
            count++;
        }
        return count == n;
    }
};

5171. 最接近的因数

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class Solution {
public:
    vector<int> closestDivisors(int num) {
        int n1 = num+1, n2 = num+2;
        vector<int> ret(2);
        int curmin = INT_MAX;
        for(int i=1; i<=sqrt(n1); i++){
            int f = n1 % i;
            if(f == 0 && abs(n1/i-i)<curmin){
                curmin = abs(n1/i-i);
                ret[0] = i; ret[1] = n1/i;
            }
        }
        for(int i=1; i<=sqrt(n2); i++){
            int f = n2 % i;
            if(f == 0 && abs(n2/i-i)<curmin){
                curmin = abs(n2/i-i);
                ret[0] = i; ret[1] = n2/i;
            }
        }
        return ret;
    }
};

5172. 形成三的最大倍数

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class Solution {
public:
    string largestMultipleOfThree(vector<int>& digits) {
        vector<vector<int>> v(3);
        int sum = 0;
        for (auto x : digits)
        {
            v[x%3].push_back(x);
            sum += x;
            sum %= 3;
        }
        vector<int> r;
        for (int i = 0; i < 3; ++ i)
        {
            sort(v[i].begin(), v[i].end(), greater<int>());
        }
        
        if (sum == 0)
        {
            for (int i = 0; i < 3; ++ i)
            {
                int c = v[i].size();
                for (int j = 0; j < c; ++ j) r.push_back(v[i][j]);
            }
        }
        else if (sum == 1)
        {
            if (v[1].size() >= 1)
            {
                for (int i = 0; i < 3; ++ i)
                {
                    int c = v[i].size();
                    if (i == 1) c --;
                    for (int j = 0; j < c; ++ j) r.push_back(v[i][j]);
                }
            }
            else
            {
                for (int i = 0; i < 3; ++ i)
                {
                    int c = v[i].size();
                    if (i == 2) c -= 2;
                    for (int j = 0; j < c; ++ j) r.push_back(v[i][j]);
                }
            }
        }
        else if (sum == 2)
        {
            if (v[2].size() >= 1)
            {
                for (int i = 0; i < 3; ++ i)
                {
                    int c = v[i].size();
                    if (i == 2) c --;
                    for (int j = 0; j < c; ++ j) r.push_back(v[i][j]);
                }
            }
            else
            {
                for (int i = 0; i < 3; ++ i)
                {
                    int c = v[i].size();
                    if (i == 1) c -= 2;
                    for (int j = 0; j < c; ++ j) r.push_back(v[i][j]);
                }
            }
        }
        
        if (r.empty()) return "";
        
        sort(r.begin(), r.end(), greater<int>());
        if (r[0] == 0) return "0";
        
        string ret;
        for (auto x : r)
            ret += x+'0';
        return ret;
    }
};
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