二分法、线段树

最新推荐文章于 2022-04-04 16:59:13 发布

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本文介绍了一种使用二分法和线段树解决查找问题的方法，并提供了完整的C++代码实现。通过递归方式在有序数组中查找指定元素，展示了两种数据结构的应用场景。

http://acm.nbut.edu.cn/Problem/view.xhtml?id=1233
二分法

//#pragma comment(linker, "/STACK:61400000,61400000")
#include <set>
#include <map>
#include <list>
#include <stack>
#include <queue>
#include <cmath>
#include <cstdio>
#include <vector>
#include <string>
#include <iomanip>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;

#define pi 3.1415926535897932385
#define LL64 __int64
#define LL long long
#define oo 2147483647
#define N 100100
#define M 210
#define INF 1e9

int a[N];

void bin(int l, int r, int v)
{
	int mid = (l + r)>>1;
	if (v == a[mid]) printf("True\n");
	else if (l == r) printf("False\n");
	else if (v < a[mid]) bin(l, mid, v);
	else bin(mid + 1, r, v);
}

int main()
{
	int n;
	
	//freopen("data.in", "r", stdin);
	//freopen("data.out", "w", stdout);
	//int _case = 1;
	//scanf("%d", &t);
	//while (t--)
	//for (int _case = 1; _case <= t; _case++)
	while (~scanf("%d", &n))
	{
		for (int i = 0; i < n; i++)
		{
			scanf("%d", &a[i]);
		}
		int m;
		scanf("%d", &m);
		while (m--)
		{
			int x;
			scanf("%d", &x);
			bin(0, n - 1, x);
		}
	}
	
	return 0;
}

线段树

//#pragma comment(linker, "/STACK:61400000,61400000")
#include <set>
#include <map>
#include <list>
#include <stack>
#include <queue>
#include <cmath>
#include <cstdio>
#include <vector>
#include <string>
#include <iomanip>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;

#define pi 3.1415926535897932385
#define LL64 __int64
#define LL long long
#define oo 2147483647
#define N 100100
#define M 210
#define INF 1e9

struct tree
{
	int l, r, mid, lv, rv;
}a[N * 3];

void init(int ll, int rr, int num)
{
	a[num].l = ll;
	a[num].r = rr;
	a[num].mid = (ll + rr)>>1;
	if (ll == rr)
	{
		scanf("%d", &a[num].lv);
		a[num].rv = a[num].lv;
	}
	else
	{
		init(ll, a[num].mid, num * 2);
		init(a[num].mid + 1, rr, num * 2 + 1);
		a[num].lv = a[num * 2].lv;
		a[num].rv = a[num * 2 + 1].rv;
	}
}

void find(int num, int x)
{
	if (a[num].l == a[num].r)
	{
		if (a[num].lv == x) printf("True\n");
		else printf("False\n");
	}
	else if (x <= a[num * 2].rv) find(num * 2, x);
	else find(num * 2 + 1, x);
}

int main()
{
	int n;
	
	//freopen("data.in", "r", stdin);
	//freopen("data.out", "w", stdout);
	//int _case = 1;
	//scanf("%d", &t);
	//while (t--)
	//for (int _case = 1; _case <= t; _case++)
	while (~scanf("%d", &n))
	{
		init(1, n, 1);
		int m;
		scanf("%d", &m);
		while (m--)
		{
			int x;
			scanf("%d", &x);
			find(1, x);
		}
	}
	
	return 0;
}