Solved problems 1025[A, B] from codeforces

Author: AliOsm

CodeForces/1025A. Doggo Recoloring.cpp

@@ -0,0 +1,34 @@
+/*
+  Idea:
+    - Implementation, Frequency array.
+*/
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n;
+string s;
+
+int main() {
+  cin >> n >> s;
+
+  if(n == 1) {
+    puts("Yes");
+    return 0;
+  }
+
+  int fr[26] = {0};
+  for(int i = 0; i < n; ++i)
+    ++fr[s[i] - 'a'];
+
+  for(int i = 0; i < 26; ++i)
+    if(fr[i] > 1) {
+      puts("Yes");
+      return 0;
+    }
+
+  puts("No");
+
+  return 0;
+}

CodeForces/1025B. Weakened Common Divisor.cpp

@@ -0,0 +1,71 @@
+/*
+  Idea:
+    - Brute force the divisors of the first pair, is there is no
+      answer, then print "No", otherwise print "Yes".
+*/
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int const N = 2e5 + 1;
+int n;
+pair<int, int> a[N];
+vector<int> d;
+set<int> st;
+
+void calc_div(int x) {
+  d.clear();
+  int sqrtx = sqrt(x) + 1;
+  for(int i = 1; i <= sqrtx; ++i) {
+    if(x % i == 0) {
+      d.push_back(i);
+
+      if(x / i != i)
+        d.push_back(x / i);
+    }
+  }
+}
+
+void solve() {
+  for(int i = 0, cur, dd; i < d.size(); ++i) {
+    if(d[i] == 1)
+      continue;
+    cur = 0;
+    dd = d[i];
+
+    if(st.count(dd) == 1)
+      continue;
+    st.insert(dd);
+
+    for(int j = 1; j < n; ++j)
+      if(a[j].first % dd == 0 || a[j].second % dd == 0)
+        ++cur;
+      else
+        break;
+
+    if(cur == n - 1) {
+      printf("%d\n", dd);
+      exit(0);
+    }
+  }
+}
+
+int main() {
+  scanf("%d", &n);
+  for(int i = 0; i < n; ++i)
+    scanf("%d %d", &a[i].first, &a[i].second);
+
+  sort(a, a + n);
+  reverse(a, a + n);
+
+  calc_div(a[0].first);
+  solve();
+
+  calc_div(a[0].second);
+  solve();
+
+  puts("-1");
+
+  return 0;
+}

CodeForces/README.md

@@ -554,6 +554,8 @@
 - [1023B. Pair of Toys](http://codeforces.com/contest/1023/problem/B)
 - [1023C. Bracket Subsequence](http://codeforces.com/contest/1023/problem/C)
 - [1023D. Array Restoration](http://codeforces.com/contest/1023/problem/D)
+- [1025A. Doggo Recoloring](http://codeforces.com/contest/1025/problem/A)
+- [1025B. Weakened Common Divisor](http://codeforces.com/contest/1025/problem/B)
 - [1027A. Palindromic Twist](http://codeforces.com/contest/1027/problem/A)
 - [1027B. Numbers on the Chessboard](http://codeforces.com/contest/1027/problem/B)
 - [1027C. Minimum Value Rectangle](http://codeforces.com/contest/1027/problem/C)