Add contest/2020-fall

Author: MaskRay

contest/2020-fall/2.cc

@@ -0,0 +1,24 @@
+// 魔术排列
+#define ALL(x) (x).begin(), (x).end()
+
+class Solution {
+public:
+  bool isMagic(vector<int>& target) {
+    int n = target.size(), r = -1;
+    vector<int> a(n), b(n);
+    iota(ALL(a), 1);
+    for (int i = 0; i < n; ) {
+      int j = i;
+      for (int k = i+1; k < n; k += 2)
+        b[j++] = a[k];
+      for (int k = i; k < n; k += 2)
+        b[j++] = a[k];
+      a.swap(b);
+      for (j = i; j < n && a[j] == target[j]; j++);
+      if (!i && j) r = j;
+      if (j < n && j-i != r) return false;
+      i = j;
+    }
+    return true;
+  }
+};

contest/2020-fall/3.cc

@@ -0,0 +1,37 @@
+// 数字游戏
+#define FOR(i, a, b) for (remove_cv<remove_reference<decltype(b)>::type>::type i = (a); i < (b); i++)
+
+class Solution {
+public:
+  vector<int> numsGame(vector<int>& nums) {
+    int n = nums.size();
+    long s0 = nums[0], s1 = 0;
+    priority_queue q0{less{}, vector{nums[0]}};
+    priority_queue q1{greater{}, vector<int>{}};
+    vector ret{0};
+    FOR(i, 1, n) {
+      int x = nums[i]-i;
+      if (x < q0.top()) {
+        q0.push(x);
+        s0 += x;
+        if (q0.size() == q1.size()+2) {
+          q1.push(q0.top());
+          s1 += q0.top();
+          s0 -= q0.top();
+          q0.pop();
+        }
+      } else {
+        q1.push(x);
+        s1 += x;
+        if (q1.size() == q0.size()+1) {
+          q0.push(q1.top());
+          s0 += q1.top();
+          s1 -= q1.top();
+          q1.pop();
+        }
+      }
+      ret.push_back((i%2 ? s1-s0 : s1-s0+q0.top()) % 1000000007);
+    }
+    return ret;
+  }
+};