round 495 ABCD

Author: fsq

1004A. Sonya and Hotels.cpp

@@ -0,0 +1,24 @@
+#include <vector>
+#include <string>
+#include <algorithm>
+#include <unordered_set>
+#include <numeric>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(false);
+    int n, d, x, y, ans=2;
+    cin >> n >> d >> x;
+    d <<= 1;
+    for (int i=1; i<n; ++i) {
+        cin >> y;
+        if (y - x > d) ans += 2;
+            else if (y - x == d) ++ans;
+        x = y;
+    }
+    cout << ans << endl;
+
+    return 0;
+}

1004B. Sonya and Exhibition.cpp

@@ -0,0 +1,19 @@
+#include <vector>
+#include <string>
+#include <algorithm>
+#include <unordered_set>
+#include <numeric>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(false);
+    int n;
+    cin >> n;
+    for (int i=0; i<n; ++i) 
+        cout << (i&1);
+    cout << endl;
+
+    return 0;
+}

1004C. Sonya and Robots.cpp

@@ -0,0 +1,40 @@
+#include <vector>
+#include <string>
+#include <algorithm>
+#include <unordered_set>
+#include <numeric>
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    ios::sync_with_stdio(false);
+ 
+    int n;
+    cin >> n;
+
+    vector<int> a(n+1);
+    for (int i=1; i<=n; ++i) cin >> a[i];
+
+    unordered_set<int> st;
+    vector<int> s(n+1);
+    for (int i=1; i<=n; ++i)
+        if (st.find(a[i])==st.end()) {
+            ++s[i];
+            st.insert(a[i]);
+        }
+
+    partial_sum(s.begin(), s.end(), s.begin());
+
+    st.clear();
+    long long ans = 0;
+    for (int i=n; i>0; --i)
+        if (st.find(a[i])==st.end()) {
+            ans += s[i-1];
+            st.insert(a[i]);
+        }
+
+    cout << ans << endl;
+    return 0;
+
+}

1004D. Sonya and Matrix.cpp

@@ -0,0 +1,130 @@
+#include <vector>
+#include <string>
+#include <algorithm>
+#include <unordered_set>
+#include <numeric>
+#include <iostream>
+#include <cstring>
+#include <cmath>
+
+using namespace std;
+
+int t;
+int a[1000007], b[1000007];
+
+void build(int n, int m, int r, int c, int b[]) {
+    for (int i=1; i<=n; ++i)
+        for (int j=1; j<=m; ++j)
+            ++b[abs(i-r)+abs(j-c)];
+}
+
+bool ok(int b[]) {
+    for (int i=0; i<=t; ++i)
+        if (a[i]!=b[i]) return false;
+    return true;
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin >> t;
+
+    int mx = 0;
+    for (int x,i=0; i<t; ++i) {
+        cin >> x;
+        mx = max(x, mx);
+        ++a[x];
+    }
+
+    if (t==1) {
+        if (a[0]==1) {
+            cout << "1 1\n1 1" << endl;
+        } else {
+            cout << -1 << endl;
+        }
+        return 0;
+    }
+
+    {
+        bool line = true;
+        for (int i=0; i<t; ++i)
+            if (a[i]!=1) {
+                line = false;
+                break;
+            }
+        if (line) {
+            cout << 1 <<' ' << t << "\n1 1" << endl;
+            return 0;
+        }
+    }
+
+    int x=-1, y=-1, i, j=0;
+    for (i=1; a[i] ;++i)
+        if (a[i]!=i*4) {
+            if (a[i]+2==i*4) x = i, y = i;
+                        else     x = i;
+            break;
+        }
+
+    if (y==-1) {
+        for (++i; a[i]==a[i-1]+2;++i);
+        y = i;
+    }
+
+    // cout << x << ' ' << y << endl;
+    bool found = false;
+
+    if (!(x==-1 || y==-1)) {
+        // case 1
+        int c1 = -1, c2 = mx+x+y, c3 = -t;
+        int delta2 = c2*c2 - 4*c1*c3;
+        if (delta2>=0 && pow((int)sqrt(delta2), 2)==delta2) {
+            int delta = sqrt(delta2);
+            vector<double> ms = {(-c2-delta) / (2.0*c1), (-c2+delta) / (2.0*c1)};
+            for (auto m : ms) 
+                if (m>0 && m==floor(m) && t%(int)m==0) {
+                    int n = t / m;
+                    memset(b, 0, sizeof(b));
+                    build(n, m, x, y, b);
+                    if (ok(b)) {
+                        found = true;
+                        cout << n << ' ' << m << '\n' << x << ' ' << y << endl;
+                        break;
+                    }
+                    memset(b, 0, sizeof(b));
+                    build(n, m, y, x, b);
+                    if (ok(b)) {
+                        found = true;
+                        cout << n << ' ' << m << '\n' << y << ' ' << x << endl;
+                        break;
+                    }
+
+                }
+
+        }
+
+        // case 2
+        if (!found) {
+            int n = x + y - 1;
+            if (t%n==0) {
+                if (x<y) swap(x, y);
+                int m = t / n;
+                memset(b, 0, sizeof(b));
+                // printf("%d %d %d %d\n", n,m,x, mx-x+2);
+                build(n, m, x, (mx-x+2), b);
+                // for (int i=0; i<=t; ++i)
+                    // cout << b[i] << ' ';cout << endl;
+                if (ok(b)) {
+                    found = true;
+                    cout << n << ' ' << m << '\n' << x << ' ' << (mx-x+2) << endl;    
+                }
+            }
+        }
+    }
+
+    if (!found)
+        cout << -1 << endl;
+
+    
+    return 0;
+
+}