poj 2488

深度遍历，记住字典序很重要

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cmath>
#include <map>
#include <algorithm>
#include <list>
#include <ctime>
#include <set>
#include <string.h>
#include <queue>
#include <cstdio>
#define CLR(arr, what) memset(arr, what, sizeof(arr))
typedef long long ll;
const int MAX = 28;
using namespace std;

int visit[MAX][MAX];
int dx[] = { -2, -2, -1, -1, 1, 1, 2, 2 };
int dy[] = { -1, 1, -2, 2, -2, 2, -1, 1 };
int row, col;
vector<int> path;
void print() {
    int sz = path.size();
    for (int i = sz / 2 - 1; i >= 0; i--) {
        cout << (char) ('A' + path[i * 2]) << path[i * 2 + 1] + 1;
    }
}
bool dfs(int total, int x, int y) {

    bool judge;
    if (x < 0 || x >= row || y < 0 || y >= col) {
        return false;
    } else if (visit[x][y] == 1) {
        return false;
    } else {
        if (total == row * col) {
            path.push_back(x);
            path.push_back(y);
            return true;
        }

        visit[x][y] = 1;
        for (int i = 0; i < 8; i++) {
            judge = dfs(total + 1, x + dx[i], y + dy[i]);
            if (judge) {
                path.push_back(x);
                path.push_back(y);
                return true;
            }
        }
        visit[x][y] = 0;
        return false;
    }
}
int main() {
    int n;
    bool judge;
    cin >> n;
    for (int i = 0; i < n; i++) {
        path.clear();
        CLR(visit, 0);
        cin >> col >> row;
        judge = dfs(1, 0, 0);
        cout << "Scenario #" << i + 1 << ":\n";
        if (judge) {
            print();
            cout << endl;
        } else {
            cout << "impossible" << endl;
        }
        cout << endl;
    }
    return 0;
}

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