poj 2010 （二分加搜索）关于深搜的一种优美的写法

最新推荐文章于 2023-09-04 13:52:44 发布

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本文探讨了深度优先搜索(DFS)在解决迷宫寻路问题中的应用，并结合二分查找算法确定最优路径条件，通过定义地图范围和障碍物，实现了从起点到终点的有效路径寻找。

#include <iostream>
#include <cstdio>
#include <iomanip>
#include <string>
#include <cstdlib>
#include <cstring>
#include <queue>
#include <set>
#include <vector>
#include <map>
#include <algorithm>
#include <cmath>
#include <stack>

#define INF 0x3f3f3f3f
#define LINF 0x3f3f3f3f3f3f3f3f
#define ll long long
#define ull unsigned long long
#define uint unsigned int

using namespace std;

int dx[] = { 0,1,-1,0 };
int dy[] = { 1,0,0,-1 };
int n, mmap[111][111], vis[111][111];

int mmin, mmax;
bool dfs(int x, int y) {
	if (x == n && y == n)return 1;
	int nx, ny;
	for (int i = 0; i < 4; i++) {
		nx = x + dx[i];
		ny = y + dy[i];
		if (mmap[nx][ny] > mmax || mmap[nx][ny] < mmin)
			continue;
		if (nx<1 || nx>n || ny<1 || ny>n||vis[nx][ny])
			continue;
		vis[nx][ny] = 1;
		if (dfs(nx, ny))return 1;
	}
	return 0;
}

bool c(int d) {
	for (int i = 0; i + d <= 110; i++) {
		memset(vis, 0, sizeof(vis));
		mmin = i, mmax = i + d;
		if ((mmap[1][1] <= i + d && mmap[1][1] >= i)
			&& dfs(1, 1))
			return 1;
	}
	return 0;
}

int main() {
	scanf("%d", &n);
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= n; j++)
			scanf("%d", &mmap[i][j]);
	int l = 0, r = 110,mid;
	while (r > l) {
		mid = (r + l) / 2;
		if (c(mid))r = mid;
		else l = mid + 1;
	}
	printf("%d\n", r);

	return 0;
}