update leetcode

Author: intfloat

leetcode/BinaryNumberWithAlternatingBits.cpp

@@ -0,0 +1,20 @@
+class Solution {
+public:
+ bool hasAlternatingBits(int n) {
+ int end = 0;
+ int nn = n;
+ while (nn > 0) {
+ nn -= nn & (1 << end);
+ ++end;
+ }
+
+ for (int i = end - 1; i >= 1; --i) {
+ bool high_bit = (n & (1 << i)) > 0;
+ bool low_bit = (n & (1 << (i - 1))) > 0;
+ if (high_bit == low_bit) {
+ return false;
+ }
+ }
+ return true;
+ }
+};

leetcode/EmployeeImportance.cpp

@@ -0,0 +1,34 @@
+/*
+// Definition for Employee.
+class Employee {
+public:
+ int id;
+ int importance;
+ vector<int> subordinates;
+};
+*/
+
+class Solution {
+public:
+ int getImportance(vector<Employee*> employees, int id) {
+ map<int, Employee*> id_to_emp;
+ for (auto& employee : employees) {
+ id_to_emp[employee->id] = employee;
+ }
+ int res = 0;
+ queue<Employee*> q;
+ if (id_to_emp.find(id) != id_to_emp.end()) {
+ q.push(id_to_emp[id]);
+ }
+
+ while (!q.empty()) {
+ Employee* tp = q.front();
+ q.pop();
+ res += tp->importance;
+ for (auto& sub_id : tp->subordinates) {
+ q.push(id_to_emp[sub_id]);
+ }
+ }
+ return res;
+ }
+};

leetcode/MaxAreaOfIsland.cpp

@@ -0,0 +1,48 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define FOR(i, n) for (int i = 0; i < (int)n; ++i)
+typedef long long ll;
+typedef pair<int, int> pii;
+
+
+int dir_x[] = {0, 0, 1, -1};
+int dir_y[] = {1, -1, 0, 0};
+
+class Solution {
+private:
+ vector<vector<bool> > visited;
+ int bfs(vector<vector<int> >& grid, int r, int c) {
+ queue<pii> q;
+ q.push({r, c});
+ visited[r][c] = true;
+ int area = 1;
+
+ while (!q.empty()) {
+ pii tp = q.front();
+ q.pop();
+ FOR(i, 4) {
+ int nr = tp.first + dir_x[i];
+ int nc = tp.second + dir_y[i];
+ if (nr < 0 || nr >= grid.size() || nc < 0 || nc >= grid[0].size()) continue;
+ if (visited[nr][nc] || grid[nr][nc] == 0) continue;
+ visited[nr][nc] = true;
+ q.push({nr, nc});
+ ++area;
+ }
+ }
+ return area;
+ }
+public:
+ int maxAreaOfIsland(vector<vector<int> >& grid) {
+ int row = grid.size();
+ int col = grid[0].size();
+ this->visited = vector<vector<bool> >(row, vector<bool>(col, false));
+
+ int res = 0;
+ FOR(i, row) FOR(j, col) {
+ if (visited[i][j] || grid[i][j] == 0) continue;
+ res = max(res, bfs(grid, i, j));
+ }
+ return res;
+ }
+};

leetcode/TopKFrequentWords.cpp

@@ -0,0 +1,21 @@
+class Solution {
+public:
+ vector<string> topKFrequent(vector<string>& words, int k) {
+ map<string, int> word_cnt;
+ for (auto& w : words) {
+ ++word_cnt[w];
+ }
+
+ vector<pair<int, string> > freq_word_pairs;
+ for (auto& it : word_cnt) {
+ freq_word_pairs.push_back({-it.second, it.first});
+ }
+ sort(freq_word_pairs.begin(), freq_word_pairs.end());
+
+ vector<string> res;
+ for (int i = 0; i < k; ++i) {
+ res.push_back(freq_word_pairs[i].second);
+ }
+ return res;
+ }
+};