POJ 2328 解题报告

这道题我是用segment tree做的。刚开始TLE，后来把cin, cout改成scanf, printf后就过了。

2823

Accepted

42344K

6641MS

C++

3335B

/* 
ID: thestor1 
LANG: C++ 
TASK: poj2823 
*/
#include <iostream>
#include <fstream>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <limits>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <cassert>

using namespace std;

void build(std::vector<pair<int, int> > &segmentTree, int left, int right, int index, std::vector<int> &nums)
{
	if (left != right)
	{
		int mid = left + ((right - left) >> 1);
		build(segmentTree, left, mid, 2 * index + 1, nums);
		build(segmentTree, mid + 1, right, 2 * index + 2, nums);
		segmentTree[index].first = min(segmentTree[2 * index + 1].first, segmentTree[2 * index + 2].first);
		segmentTree[index].second = max(segmentTree[2 * index + 1].second, segmentTree[2 * index + 2].second);
	}
	else
	{
		// cout << "[build]index: " << index << ", left: " << left << ", nums[left]: " << nums[left] << endl;
		segmentTree[index].first = segmentTree[index].second = nums[left];
	}
}

void query(std::vector<pair<int, int> > &segmentTree, int left, int right, int index, int lindex, int rindex, pair<int, int> &minmax)
{
	if (lindex <= left && right <= rindex)
	{
		minmax.first = min(minmax.first, segmentTree[index].first);
		minmax.second = max(minmax.second, segmentTree[index].second);
		return;
	}

	if (left != right)
	{
		int mid = left + ((right - left) >> 1);
		if (rindex <= mid)
		{
			query(segmentTree, left, mid, 2 * index + 1, lindex, rindex, minmax);
		}	
		else if (mid + 1 <= lindex)
		{
			query(segmentTree, mid + 1, right, 2 * index + 2, lindex, rindex, minmax);
		}
		else
		{
			query(segmentTree, left, mid, 2 * index + 1, lindex, rindex, minmax);
			query(segmentTree, mid + 1, right, 2 * index + 2, lindex, rindex, minmax);	
		}
	}
}

void printSegmentTree(std::vector<pair<int, int> > &segmentTree, int left, int right, int index)
{
	cout << "index: " << index << " (" << segmentTree[index].first << ", " << segmentTree[index].second << ")" << endl;
	if (left != right)
	{
		int mid = left + ((right - left) >> 1);
		printSegmentTree(segmentTree, left, mid, 2 * index + 1);
		printSegmentTree(segmentTree, mid + 1, right, 2 * index + 2);
	}
}

int main()
{
	// std::ios::sync_with_stdio(false);
	int n, k;
	// cin >> n >> k;
	scanf("%d%d", &n, &k);
	std::vector<int> nums(n);
	for (int i = 0; i < n; ++i)
	{
		// cin >> nums[i];
		scanf("%d", &nums[i]);
	}

	// cout << "nums:" << endl;
	// for (int i = 0; i < n; ++i)
	// {
	// 	cout << nums[i] << " ";
	// }
	// cout << endl;

	std::vector<pair<int, int> > segmentTree(4 * n);
	build(segmentTree, 0, n - 1, 0, nums);

	// printSegmentTree(segmentTree, 0, n - 1, 0);

	std::vector<pair<int, int > > minmaxs(n - k + 2, make_pair(INT_MAX, INT_MIN));
	for (int i = 0; i + k - 1 < n; ++i)
	{
		// i, i + k - 1;
		query(segmentTree, 0, n - 1, 0, i, i + k - 1, minmaxs[i]);
	}

	for (int i = 0; i + k - 1 < n; ++i)
	{
		// cout << minmaxs[i].first << " ";
		printf("%d ", minmaxs[i].first);
	}
	// cout << endl;
	printf("\n");

	for (int i = 0; i + k - 1 < n; ++i)
	{
		// cout << minmaxs[i].first << " ";
		printf("%d ", minmaxs[i].second);
	}
	// cout << endl;
	printf("\n");
	
	return 0;  
}