36 lines
494 B
C++
36 lines
494 B
C++
#include <iostream>
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int main() {
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int n;
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std::cin >> n;
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int* arr = new int[n];
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for (int i = 0; i < n; ++i) {
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std::cin >> arr[i];
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}
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for (int i = 0; i < n; ++i) {
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if (2 * i + 1 >= n) {
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break;
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}
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if (arr[i] > arr[2 * i + 1]) {
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std::cout << "NO";
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return 0;
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}
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if (2 * i + 2 >= n) {
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break;
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}
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if (arr[i] > arr[2 * i + 2]) {
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std::cout << "NO";
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return 0;
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}
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}
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std::cout << "YES";
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delete[] arr;
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return 0;
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}
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