Submission #1007996

#	Time	Username	Problem	Language	Result	Execution time	Memory
1007996		The_Samurai	Horses (IOI15_horses)	C++17	100 / 100	232 ms	53348 KiB

horses

#include "horses.h"
#include "bits/stdc++.h"
using namespace std;
const int mod = 1e9 + 7;
using ll = long long;

struct SegTreeY {
	vector<int> tree;
	int size;
	int neutral_element = -1e9;

	int merge(int a, int b) {
		return max(a, b);
	}
	
	void build(const vector<int> &a) {
		size = 1;
		while (size < a.size()) size *= 2;
		tree.assign(2 * size, neutral_element);
		for (int i = size; i < size + a.size(); i++) tree[i] = a[i - size];
		for (int i = size - 1; i > 0; i--) tree[i] = merge(tree[i << 1], tree[i << 1 | 1]);
	}

	void upd(int i, int v) {
		i += size;
		tree[i] = v;
		for (; i > 1; i >>= 1) tree[i >> 1] = merge(tree[i], tree[i ^ 1]);
	}

	int get(int l, int r) {
		if (l > r) return neutral_element;
		int res = neutral_element;
		for (l += size, r += size + 1; l < r; l >>= 1, r >>= 1) {
			if (l & 1) res = merge(res, tree[l++]);
			if (r & 1) res = merge(res, tree[--r]);
		}
		return res;
	}
};

struct SegTreeX {
	vector<int> tree;
	int size;
	int neutral_element = 1;

	int merge(int a, int b) {
		return 1ll * a * b % mod;
	}
	
	void build(const vector<int> &a) {
		size = 1;
		while (size < a.size()) size *= 2;
		tree.assign(2 * size, neutral_element);
		for (int i = size; i < size + a.size(); i++) tree[i] = a[i - size];
		for (int i = size - 1; i > 0; i--) tree[i] = merge(tree[i << 1], tree[i << 1 | 1]);
	}

	void upd(int i, int v) {
		i += size;
		tree[i] = v;
		for (; i > 1; i >>= 1) tree[i >> 1] = merge(tree[i], tree[i ^ 1]);
	}

	int get(int l, int r) {
		if (l > r) return neutral_element;
		int res = neutral_element;
		for (l += size, r += size + 1; l < r; l >>= 1, r >>= 1) {
			if (l & 1) res = merge(res, tree[l++]);
			if (r & 1) res = merge(res, tree[--r]);
		}
		return res;
	}
};

int n;
vector<int> x, y;
SegTreeX sgX;
SegTreeY sgY;
set<int, greater<>> st;

int get_ans() {
	vector<tuple<int, int, int>> vec;
	int last = n;
	__int128_t mul = 1;
	for (int i: st) {
		mul *= x[i];
		vec.emplace_back(i, x[i], sgY.get(i, last - 1));
		last = i;
		if (mul > ll(1e9)) break;
	}
	if (vec.empty()) {
		return sgY.get(0, n - 1);
	}
	reverse(vec.begin(), vec.end());
	__int128_t best = 1;
	mul = 1;
	for (auto [i, v1, v2]: vec) {
		// cout << i << ' ' << v1 << ' ' << v2 << endl;
		mul *= v1;
		best = max(best, mul * v2);
	}
	if (best <= ll(1e9) and best * sgX.get(0, get<0>(vec[0]) - 1) < sgY.get(0, n - 1)) {
		best = sgY.get(0, n - 1);
	} else {
		best = best % mod * sgX.get(0, get<0>(vec[0]) - 1) % mod;     
	}
	return best;
}

int init(int N, int X[], int Y[]) {
	n = N;
	x.resize(n), y.resize(n);
	for (int i = 0; i < n; i++) x[i] = X[i], y[i] = Y[i];
	sgX.build(x);
	sgY.build(y);
	for (int i = 0; i < n; i++) {
		if (x[i] > 1) st.insert(i);
	}
	return get_ans();
}

int updateX(int pos, int val) {
	if (x[pos] > 1) st.erase(pos);
	x[pos] = val;
	sgX.upd(pos, val);
	if (x[pos] > 1) st.insert(pos);
	return get_ans();
}

int updateY(int pos, int val) {
	y[pos] = val;
	sgY.upd(pos, val);
	return get_ans();
}

Compilation message (stderr)

horses.cpp: In member function 'void SegTreeY::build(const std::vector<int>&)':
horses.cpp:18:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |   while (size < a.size()) size *= 2;
      |          ~~~~~^~~~~~~~~~
horses.cpp:20:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |   for (int i = size; i < size + a.size(); i++) tree[i] = a[i - size];
      |                      ~~^~~~~~~~~~~~~~~~~
horses.cpp: In member function 'int SegTreeX::merge(int, int)':
horses.cpp:47:22: warning: conversion from 'long long int' to 'int' may change value [-Wconversion]
   47 |   return 1ll * a * b % mod;
      |          ~~~~~~~~~~~~^~~~~
horses.cpp: In member function 'void SegTreeX::build(const std::vector<int>&)':
horses.cpp:52:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   52 |   while (size < a.size()) size *= 2;
      |          ~~~~~^~~~~~~~~~
horses.cpp:54:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |   for (int i = size; i < size + a.size(); i++) tree[i] = a[i - size];
      |                      ~~^~~~~~~~~~~~~~~~~
horses.cpp: In function 'int get_ans()':
horses.cpp:107:9: warning: conversion from '__int128' to 'int' may change value [-Wconversion]
  107 |  return best;
      |         ^~~~

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