Solved problems 1009[A, B, D] from codeforces

Author: AliOsm

CodeForces/1009A. Game Shopping.cpp

@@ -0,0 +1,26 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int const N = 1001;
+int n, m, c[N], a[N];
+
+int main() {
+  scanf("%d %d", &n, &m);
+  for(int i = 0; i < n; ++i)
+    scanf("%d", c + i);
+  for(int i = 0; i < m; ++i)
+    scanf("%d", a + i);
+
+  int res = 0;
+  for(int i = 0, cur = 0; i < n; ++i) {
+    if(a[cur] >= c[i])
+      ++cur, ++res;
+    if(cur >= m)
+      break;
+  }
+
+  printf("%d\n", res);
+
+  return 0;
+}

CodeForces/1009B. Minimum Ternary String.cpp

@@ -0,0 +1,40 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int const N = 1e5 + 1;
+char s[N], sol[N];
+
+int main() {
+  scanf("%s", s);
+  int len = strlen(s);
+
+  int cnt = 0;
+  for(int i = 0; i < len; ++i)
+    cnt += s[i] == '1';
+
+  for(int i = 0, j = 0; i < len; ++i)
+    if(s[i] != '1')
+      sol[j++] = s[i];
+
+  for(int i = 0; i < len; ++i)
+    if(s[i] == '2')
+      break;
+    else if(s[i] != '1')
+      putchar('0');
+
+  for(int i = 0; i < cnt; ++i)
+    putchar('1');
+
+  bool ok = false;
+  for(int i = 0; i < len; ++i) {
+    if(s[i] == '2')
+      ok = true;
+    if(ok && s[i] != '1')
+      putchar(s[i]);
+  }
+
+  puts("");
+
+  return 0;
+}

CodeForces/1009D. Relatively Prime Graph.cpp

@@ -0,0 +1,67 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int const N = 1e5 + 1;
+int n, m, v;
+pair<int, int> phi[N];
+set<pair<int, int> > e;
+
+void print(int x, int &cnt) {
+  for(int i = 1; cnt > 0 && i <= n; ++i)
+    if(i != x && __gcd(x, i) == 1) {
+      if(e.count({min(x, i), max(x, i)}) == 1)
+        continue;
+      e.insert({min(x, i), max(x, i)});
+      printf("%d %d\n", x, i), --cnt;
+    }
+}
+
+int main() {
+  scanf("%d %d", &n, &m);
+
+  for(int i = 1; i <= n; ++i)
+    phi[i].first = phi[i].second = i;
+
+  for(int p = 2; p <= n; ++p)
+    if(phi[p].first == p) {
+      phi[p].first = p - 1;
+
+      for(int i = 2 * p; i <= n; i += p)
+        phi[i].first = (phi[i].first / p) * (p - 1);
+    }
+
+  long long to = 0;
+  for(int i = 1; i <= n; ++i)
+    to += phi[i].first;
+
+  if(to - 1 < m || m < n - 1) {
+    puts("Impossible");
+    return 0;
+  }
+
+  puts("Possible");
+
+  for(int i = n; i > 0; --i)
+    if(phi[i].first == phi[i].second - 1) {
+      v = phi[i].second;
+      break;
+    }
+  
+  for(int i = 1; i <= n; ++i) {
+    if(i == v)
+      continue;
+
+    printf("%d %d\n", v, i);
+    e.insert({min(v, i), max(v, i)});
+  }
+  m -= (n - 1);
+
+  sort(phi + 1, phi + n + 1);
+  reverse(phi + 1, phi + n + 1);
+
+  for(int i = 1; m > 0 && i <= n; ++i)
+    print(phi[i].second, m);
+
+  return 0;
+}

CodeForces/README.md

@@ -488,3 +488,6 @@
 - [1005C. Summarize to the Power of Two](http://codeforces.com/contest/1005/problem/C)
 - [1005D. Polycarp and Div 3](http://codeforces.com/contest/1005/problem/D)
 - [1005E1. Median on Segments (Permutations Edition)](http://codeforces.com/contest/1005/problem/E1)
+- [1009A. Game Shopping](http://codeforces.com/contest/1009/problem/A)
+- [1009B. Minimum Ternary String](http://codeforces.com/contest/1009/problem/B)
+- [1009D. Relatively Prime Graph](http://codeforces.com/contest/1009/problem/D)