daily: Nov21 and Nov22

daily/Nov20.cc

@@ -0,0 +1,38 @@
+#include <iostream>
+#include <numeric>
+using namespace std;
+
+class Solution {
+ public:
+  vector<int> shortestDistanceAfterQueries(int n, vector<vector<int>>& queries) {
+    vector<int> fa(n - 1);
+    iota(fa.begin(), fa.end(), 0);
+
+    auto find = [&](int x) -> int {
+      int rt = x;
+      while (fa[rt] != rt) {
+        rt = fa[rt];
+      }
+      while (fa[x] != rt) {
+        int tmp = fa[x];
+        fa[x] = rt;
+        x = tmp;
+      }
+      return rt;
+    };
+
+    vector<int> ans(queries.size());
+    int cnt = n - 1; // num union find
+    for (int qi = 0; qi < queries.size(); qi++) {
+      int l = queries[qi][0], r = queries[qi][1] - 1;
+      int fr = find(r);
+      for (int i = find(l); i < r; i = find(i + 1)) {
+        fa[i] = fr;
+        cnt--;
+      }
+      ans[qi] = cnt;
+    }
+    return ans;
+  }
+
+};

daily/Nov21.cc

@@ -0,0 +1,27 @@
+#include <iostream>
+using namespace std;
+
+class Solution {
+ public:
+  /**
+   * @brief LC1056: confusingNumber
+   * Unordered map, time: O(N), Space: O(N)
+   *
+   * @param n
+   * @return true
+   * @return false
+   */
+  bool confusingNumber(int n) {
+    unordered_map<char, char> mp = {
+        {'0', '0'}, {'1', '1'}, {'6', '9'}, {'8', '8'}, {'9', '6'}};
+    auto numstr = to_string(n);
+    string newstr = "";
+    for (auto& ch : numstr) {
+      if (!mp.count(ch)) {
+        return false;
+      }
+      newstr = mp[ch] + newstr;
+    }
+    return newstr != numstr;
+  }
+};