【线段树】line

最新推荐文章于 2024-09-13 19:36:07 发布

原创最新推荐文章于 2024-09-13 19:36:07 发布 · 520 阅读

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#线段树

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本文介绍了一个结合线段树与并查集的数据结构问题解决方案。通过使用线段树进行区间更新与查询，同时利用并查集管理元素间的连接关系，解决了涉及区间操作与元素合并的问题。代码中详细展示了数据结构的设计与实现过程。

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#include <cstdio>
#include <iostream>

using namespace std;

int read()
{
	int n = 0, sign = 1; char c = getchar();
	while(c < '0' || c > '9') {if(c == '-') sign = -1; c = getchar(); }
	while(c >= '0' && c <= '9') { n = n*10 + c-'0'; c = getchar(); }
	return n * sign;
}

const int Nmax = 100005;
const int Mmax = 100005;

int N, M;
bool is_line[Mmax];
struct line{
	int l, r, h, R;
}li[Mmax];
int q[Mmax];

inline void Union(int a, int b)
{
	int temp = li[a].R;
	li[a].R = b; li[b].R = temp;
}

#define lc (u << 1)
#define rc (u << 1 | 1)

namespace SegmentTree{
	int lazyc[4 * Nmax], lazyh[4 * Nmax];
	
	inline void push_down(int u)
	{
		if (lazyh[lc] < lazyh[u]) 
		{
			lazyh[lc] = lazyh[u];
			lazyc[lc] = lazyc[u];
		}
		if (lazyh[rc] < lazyh[u])
		{
			lazyh[rc] = lazyh[u];
			lazyc[rc] = lazyc[u];
		}
		lazyh[u] = lazyc[u] = 0;
	}
	
	inline void Add(int u, int l, int r, int L, int R, int color, int high)
	{
		if (lazyh[u] > high) return;
		if (L == l && r == R)
		{
			lazyc[u] = color;
			lazyh[u] = high;
			return;
		}
		
		int mid = (l + r) >> 1; push_down(u);
		if (R <= mid) Add(lc, l, mid, L, R, color, high);
		else if (L > mid) Add(rc, mid + 1, r, L, R, color, high);
		else 
		{
			Add(lc, l, mid, L, mid, color, high);
			Add(rc, mid + 1, r, mid + 1, R, color, high); 
		}
	}
	
	inline int Query(int u, int l, int r, int pos)
	{
		if (l == r) return lazyc[u];
		
		int mid = (l + r) >> 1; push_down(u);
		if (pos <= mid) return Query(lc, l, mid, pos);
		else return Query(rc, mid + 1, r, pos);
	}
}

int main()
{
	freopen("line.in", "r", stdin);
	freopen("line.out", "w", stdout);
	
	N = read(), M = read();
	int cnt1 = 0, cnt2 = 0;
	li[0].h = li[0].R = -1;
	for (int i = 1; i <= M; ++i)
	{
		int sign = read();
		if (sign == 1) {
			is_line[i] = 1; ++cnt1;
			li[cnt1].l = read(), li[cnt1].r = read(); int lower = read();
			Union(lower, cnt1);
		} else q[++cnt2] = read();
	}
	for (int i = 0, cnt = 0; ~i; i = li[i].R, ++cnt) li[i].h = cnt;
	
	using namespace SegmentTree; cnt1 = cnt2 = 0;
	for (int i = 1; i <= M; ++i) 
	{
		if(is_line[i])
		{
			line temp = li[++cnt1];
			Add(1, 1, N, temp.l, temp.r, cnt1, temp.h);
		} 
		else printf("%d\n", Query(1, 1, N, q[++cnt2]));
	}
	
	return 0;
}