Hdu1010Tempter of the Bone 深搜+剪枝

题意：输入x,y,t.以及一个x行y列的地图，起点‘S’终点‘D’地板‘.’墙壁‘X’；判断能否从S正好走t步到D。

题解：dfs，奇偶性减枝，剩余步数剪枝。

ps:帮室友Debug的题：打错了两个字母。题目看错。没有初始化map。orz ...不过我dfs也不熟，更别说剪枝了。

//#include <bits/stdc++.h>
#define  _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <string>
#include <string.h>
#include <algorithm>
using namespace std;
#define LL long long
int n, m, T;
int si, sj, ei, ej;
char a[][];
int map[][];
int dir[][] = { { , },{ -, },{ , },{ ,- } };
int check(int i, int j, int t) {
    if (i< || i >= n || j< || j >= m || map[i][j] || a[i][j] == 'X') return false;

    return true;
}
bool dfs(int i, int j, int t) {

    if (i == ei&&j == ej&&t==T) return true;
    if (t>=T) return false;
    map[i][j] = ;
    for (int k = ; k<; k++) {
        int di = i + dir[k][];
        int dj = j + dir[k][];
        if (!check(di, dj, t + )) continue;
        if (dfs(di, dj, t + ))
            return true;
        map[di][dj] = ;
    }
    return false;
}
int main() {
    while (~scanf("%d%d%d", &n, &m, &T)) {
        if (n ==  && m ==  && T == ) break;
        memset(map, , sizeof(map));
        for (int i = ; i<n; i++)
            scanf("%s", a[i]);
        int ok = ;
        for (int i = ; i<n; i++) {
            for (int j = ; j<m; j++) {
                if (a[i][j] == 'D') {
                    ei = i; ej = j;
                    ok++;
                }
                if (a[i][j] == 'S') {
                    si = i; sj = j;
                    ok++;
                }
                if (ok == ) break;
            }
            if (ok == ) break;
        }
        if ((T - (abs(ei - si) + abs(ej - sj))) %  || (T - (abs(ei - si) + abs(ej - sj)))<) printf("NO\n");
        else if (dfs(si, sj,)) printf("YES\n");
        else printf("NO\n");
    }
    return ;
}