LeetCode 232场周赛

232场周赛

class Solution { // 暴力
public:
    bool areAlmostEqual(string s1, string s2) {
        int len = s1.length();
        int cnt = 0;
        int idx1 = 0, idx2 = 0;
        string temp;
        if (s1 == s2) return true;
        for (int i = 0; i < len; i++) {
            for (int j = i; j < len; j++) {
                temp = s1;
                char c = s1[i];
                temp[i] = temp[j];
                temp[j] = c;
                if (temp == s2) return true;
            }
        }
        
        return false;
    }
};

class Solution { // 最大度数的点
public:
    int findCenter(vector<vector<int>>& edges) {
        int n = edges.size();
        map<int, int> m;
        int max = 0, idx = -1;
        for (int i = 0; i < n; i++) {
            int a = edges[i][0], b = edges[i][1];
            if (m.count(a))
                m[a]++;
            else {
                m[a] = 1;
            }
            if (max < m[a]) max = m[a], idx = a;
            if (m.count(b))
                m[b]++;
            else {
                m[b] = 1;
            }
            if (max < m[b]) max = m[b], idx = b;
            
        }
        return idx;
        
    }
};

class Solution { // 自定义结构体的排序 + 优先队列
    typedef struct Class{
        double pass, total;
        
        bool operator < (const Class &x) const{
            
            double a = (pass + 1) / (total + 1) - pass/total;
            double b = (x.pass + 1) / (x.total + 1) - x.pass / x.total;
           return a < b;
      }
    }C;
public:
    double maxAverageRatio(vector<vector<int>>& classes, int extraStudents) {
        int n = classes.size();
        priority_queue<C> pq;;
        for (int i = 0; i < n; i++) {
            pq.push(C{(double)classes[i][0],(double)classes[i][1]});
        }
        while (extraStudents) {
            C c = pq.top();
            pq.pop();
            c.pass = c.pass + 1;
            c.total = c.total + 1;
            pq.push(c);
            extraStudents--;
        }
        double ans = 0;
        while (pq.size()) {
            C x = pq.top();
            pq.pop();
            //cout << x.pass << x.total << endl;
            ans += (x.pass) / (x.total);
        }
        return ans / n;
    }
};

class Solution {// 双向优先队列
// 类似的题目：直方图中最大的矩形
public:
    int maximumScore(vector<int>& nums, int k) {
        int n = nums.size();
        vector<int> h(n + 2, - 1), l(n + 2), r(n + 2), stk(n + 2);
        for (int i = 1; i <= n; i++) h[i] = nums[i - 1];
        
        int tt = 0;
        stk[0] = 0;
        for (int i = 1; i <= n; i++) {
            while (h[stk[tt]] >= h[i] ) tt--; // 栈顶当前元素比h[i]大就先弹栈
            l[i] = stk[tt]; // s记录i的左向 第一个比h[i]小的元素下标
            stk[++tt] = i; // 将当前元素压栈
        }
        
        // 相当于逆向来了一遍求左向的过程
        tt = 0;
        stk[0] = n + 1;
        for (int i = n; i; i--) {
            while (h[stk[tt]] >= h[i] ) tt--; // 栈顶当前元素比h[i]大就先弹栈
            r[i] = stk[tt]; // s记录i的左向 第一个比h[i]小的元素下标
            stk[++tt] = i; // 将当前元素压栈
        }
        k++; // 因为下标都被扩大了1 所以+1
        int res = 0;
        for (int i = 1; i <= n; i++) {
            if (l[i] < k && r[i] > k)
                res = max(res, (r[i] - l[i] + 1 - 2) * h[i]);
        }
        return res;
    }
};