hdu 1010

来源：互联网发布：哪个论坛源码好移动版编辑：程序博客网时间：2024/06/02 07:18

嗯....这题我交了27次QAQ

剪枝剪枝剪枝，重要的事情说三遍！奇偶剪枝是很重要的然后各种初始化和return也一定要写，回溯的时候记得还原修改为'X'的路径。

说到底还是我太弱了....

#include<iostream>#include<cstdio>#include<cstring>#include<cmath>using namespace std;int n,m,t,di,dj;bool ok;int dr[4][2] = {{1,0},{-1,0},{0,1},{0,-1}};char a[10][10];void dfs(int x, int y, int cnt){if (x==di && y==dj && cnt==t){ok = true;return;}if (ok)return;if (x<1 || y<1 || x>n || y>m){return;}int temp = abs(t-cnt) - abs(x-di) -abs(y-dj);if (temp<0 || temp%2!=0) // jioujianzhi{return;}int bi,bj;bi = bj = 0;for (int i=0; i<4; i++){bi = x + dr[i][0];bj = y + dr[i][1];if (a[bi][bj] != 'X'){a[bi][bj] = 'X';dfs(bi,bj,cnt+1);a[bi][bj] = '.';}}return;}int main(){while (cin >> n >> m >> t){int w = 0;memset(a,'X',sizeof(a));int si,sj;si = sj = 0;if (n==0 && m==0 && t==0){break;}for (int i=1; i<=n; i++){scanf("%s",&a[i][1]);getchar();for (int j=1; j<=m; j++){if (a[i][j] == 'S'){si = i;sj = j;}if (a[i][j] == 'D'){di = i;dj = j;}if (a[i][j] == 'X'){w++;}}}if (n*m-w <= t) //jianzhi{printf("NO\n");continue;}a[si][sj] = 'X';dfs(si,sj,0);if (ok)printf("YES\n");elseprintf("NO\n");ok = false;}return 0;}

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