京东后端开发笔试-5.14
笔试题分为两部分,选择题30题+编程题2题
编程题一:加密算法
字符串s打乱顺序后,前后加上任意字符串变为s‘,给定N组s和s'判断加密是否成功。
#include <iostream> #include <string> #include <vector> using namespace std; bool isValid(string s0, string s1) { vector<int> hash(26,0); for (int i = 0; i < s0.size(); i++) { hash[s0[i] - 'a']++; } int left = 0; int count = s0.size(); for (int i = 0; i < s1.size(); i++) { hash[s1[i] - 'a']--; while (left < s1.size() && hash[s1[i] - 'a'] < 0) { hash[s1[left] - 'a']++; left++; } if (i - left + 1 == count) return true; } return false; } int main() { int N; cin >> N; for (int i = 0; i < N; i++) { string s0, s1; cin >> s0 >> s1; if (isValid(s0, s1)) { cout << "YES" << endl; } else { cout << "NO" << endl; } } return 0; }编程题二:树上拓扑
对于无根树进行拓扑排序。第一行输入N代表树的个数,下一行N-1个整数,[f2,f3,...fn] 代表i与fi之间有边。
// // Created by Mozi on 2022/5/14. // #include <iostream> #include <vector> #include <queue> using namespace std; /* * 题目:树上拓扑 * 样例输入: * 6 * 1 2 1 3 3 */ //创建树数组 vector<int> getTrees(int n) { vector<int> trees(n - 1); for (int i = 0; i < n - 1; i++) { cin >> trees[i]; } return trees; } vector<int> toposort(int n, vector<int>& trees) { vector<int> ret; vector<vector<int>> edges(n + 1); //边 vector<int> index(n + 1); //每个树相邻的树个数 for (int i = 0; i < trees.size(); i++) { edges[i + 2].emplace_back(trees[i]); edges[trees[i]].emplace_back(i + 2); index[i + 2]++; index[trees[i]]++; } //BFS广度优先 queue<int> q; for (int i = 1; i <= n; i++) { if (index[i] == 1) { q.push(i); } } while (!q.empty()) { int cur = q.front(); q.pop(); ret.emplace_back(cur); for (auto e : edges[cur]) { index[e]--; if (index[e] == 1) { q.push(e); } } } return ret; } int main() { int n; cin >> n; vector<int> trees = getTrees(n); //length:n-1 vector<int> ret = toposort(n, trees); for (int i = 0; i < ret.size(); i++) { if (i > 0) { cout << " "; } cout << ret[i]; } cout << endl; return 0; }