Submission #929186

#	Time	Username	Problem	Language	Result	Execution time	Memory
929186		OAleksa	Horses (IOI15_horses)	C++14	17 / 100	307 ms	54076 KiB

horses

#include "horses.h"
#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int inf = 1e9 + 69;
const int N = 5e5 + 69;
int n, a[N], b[N], c[N], p[4 * N], g[4 * N];
set<int> st;
int mul(int a, int b) {
   long long r = 1ll * a * b;
   if (r >= mod)
      r %= mod;
   return r;
}
void modify(int v, int tl, int tr, int pos, int x) {
   if (tl == tr)
      p[v] = g[v] = x;
   else {
      int mid = (tl + tr) / 2;
      if (pos <= mid)
         modify(v * 2, tl, mid, pos, x);
      else
         modify(v * 2 + 1, mid + 1, tr, pos, x);
      if (p[v * 2] > inf / p[v * 2 + 1])
         p[v] = -1;
      else
         p[v] = p[v * 2] * p[v * 2 + 1];
      g[v] = mul(g[v * 2], g[v * 2 + 1]);
   }
}
int get(int v, int tl, int tr, int l, int r) {
   if (tl > r || tr < l)
      return 1;
   else if (tl >= l && tr <= r)
      return p[v];
   else {
      int mid = (tl + tr) / 2;
      auto l1 = get(v * 2, tl, mid, l, r);
      auto r1 = get(v * 2 + 1, mid + 1, tr, l, r);
      if (l1 == -1 || r1 == -1 || l1 > inf / r1)
         return -1;
      return l1 * r1;
   }
}
int Get(int v, int tl, int tr, int l, int r) {
   if (tl > r || tr < l)
      return 1;
   else if (tl >= l && tr <= r)
      return g[v];
   else {
      int mid = (tl + tr) / 2;
      return mul(Get(v * 2, tl, mid, l, r), Get(v * 2 + 1, mid + 1, tr, l, r));
   }
}
int Better(int i, int j) {
   if (i > j)
      swap(i, j);
   int x = get(1, 1, n, i + 1, j);
   if (x < 0 || x > inf / b[j])
      return j;
   return (b[i] > x * b[j] ? i : j);
}
int Solve() {
   long long ans = 1, x = a[1];
   int bst = 1;
   st.insert(1);
   for (int i = 2;i <= n;i++) {
      if (x > inf / a[i]) {
         x = 1;
         bst = i;
      }
      else {
         x *= a[i];
         if (b[i] > b[bst] / x) {
            x = 1;
            bst = i;
            st.insert(i);
         }
      }
   }
   for (int i = 1;i <= bst;i++)
      ans = mul(ans, a[i]);
   return mul(ans, b[bst]);
}
int Result(int i) {
   return mul(Get(1, 1, n, 1, i), b[i]);
}
int init(int N, int X[], int Y[]) {
   n = N;
   fill(p, p + 4 * n + 1, 1);
   fill(g, g + 4 * n + 1, 1);
   for (int i = 1;i <= n;i++) {
      a[i] = X[i - 1], b[i] = Y[i - 1];
      modify(1, 1, n, i, a[i]);
   }
   return Solve();
}

int updateX(int pos, int val) {
   pos++;
   a[pos] = val;
   modify(1, 1, n, pos, a[pos]);
   auto u = st.lower_bound(pos);
   if (u != st.begin()) {
      if (Better(*--u, pos) == pos)
         st.insert(pos);
      else if (st.count(pos))
         st.erase(pos);
   }
   u = st.upper_bound(pos);
   while (u != st.end() && Better(*u, pos) == pos) {
      st.erase(u);
      u = st.upper_bound(pos);
   }
   assert(!st.empty());
	return Result(*st.rbegin());
}

int updateY(int pos, int val) {
   pos++;
	b[pos] = val;
	auto u = st.lower_bound(pos);
   if (u != st.begin()) {
      if (Better(*--u, pos) == pos)
         st.insert(pos);
      else if (st.count(pos))
         st.erase(pos);
   }
   u = st.upper_bound(pos);
   while (u != st.end() && Better(*u, pos) == pos) {
      st.erase(u);
      u = st.upper_bound(pos);
   }
   assert(!st.empty());
	return Result(*st.rbegin());
}
/*
3
2 1 3
3 4 1
1
2 1 2

*/

Compilation message (stderr)

horses.cpp: In function 'int mul(int, int)':
horses.cpp:9:20: warning: declaration of 'b' shadows a global declaration [-Wshadow]
    9 | int mul(int a, int b) {
      |                ~~~~^
horses.cpp:7:14: note: shadowed declaration is here
    7 | int n, a[N], b[N], c[N], p[4 * N], g[4 * N];
      |              ^
horses.cpp:9:13: warning: declaration of 'a' shadows a global declaration [-Wshadow]
    9 | int mul(int a, int b) {
      |         ~~~~^
horses.cpp:7:8: note: shadowed declaration is here
    7 | int n, a[N], b[N], c[N], p[4 * N], g[4 * N];
      |        ^
horses.cpp:13:11: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   13 |    return r;
      |           ^
horses.cpp: In function 'int Solve()':
horses.cpp:82:17: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   82 |       ans = mul(ans, a[i]);
      |                 ^~~
horses.cpp:83:15: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   83 |    return mul(ans, b[bst]);
      |               ^~~
horses.cpp: In function 'int init(int, int*, int*)':
horses.cpp:88:14: warning: declaration of 'N' shadows a global declaration [-Wshadow]
   88 | int init(int N, int X[], int Y[]) {
      |          ~~~~^
horses.cpp:6:11: note: shadowed declaration is here
    6 | const int N = 5e5 + 69;
      |           ^

• Subtask 1: 17 / 17
• Subtask 2: 0 / 17
• Subtask 3: 0 / 20
• Subtask 4: 0 / 23
• Subtask 5: 0 / 23