POJ 1321 棋盘问题

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网上代码1:

#include<stdio.h>#include<string.h>int n,k,vis[15],ans;char mat[15][15];void dfs(int cur,int num){  if(num==k)  {    ans++;    return;  }  for(int i=cur;i<n;i++)    for(int j=0;j<n;j++)      if(mat[i][j]=='#' && !vis[j])      {        vis[j]=1;        dfs(i+1,num+1);        vis[j]=0;      }}int main(){  while(~scanf("%d %d%*c",&n,&k) && n!=-1 && k!=-1)  {    memset(vis,0,sizeof(vis));    int i;    for(i=0;i<n;i++)      gets(mat[i]);    ans=0;    dfs(0,0);    printf("%d\n",ans);  }  return 0;}

网站代码2:

#include<iostream>#include<cstdio>#include<cstring>using namespace std;char a[10][10];     //记录棋盘位置int book[10];        //记录一列是否已经放过棋子int n,k;int total,m;    //total 是放棋子的方案数 ，m是已放入棋盘的棋子数目void DFS(int cur){    if(k==m)    {        total++;        return ;    }    if(cur>=n)    //边界        return ;    for(int j=0; j<n; j++)        if(book[j]==0 && a[cur][j]=='#')  //判断条件        {            book[j]=1;           //标记            m++;                             DFS(cur+1);            book[j]=0;           //改回来方便下一行的判断            m--;        }    DFS(cur+1);                //到下一行}int main(){    int i,j;    while(scanf("%d%d",&n,&k)&&n!=-1&&k!=-1) //限制条件    {        total=0;        m=0;        for(i=0; i<n; i++)            scanf("%s",&a[i]);        memset(book,0,sizeof(book));        DFS(0);        printf("%d\n",total);    }    return 0;}

my:

#include <algorithm>#include <iostream>#include <stdio.h>#include <string.h>#include <stdlib.h>using namespace std;char map[15][15];int book[15];int n, k;int ans;int m;void dfs(int cur){    if(m == k){        ans++;        return ;    }    if(cur >= n)    return;    for(int j = 0;j < n;j++){        if(!book[j]&&map[cur][j]=='#'){            m++;            book[j] = 1;            dfs(cur+1);            book[j] = 0;            m--;        }    }    dfs(cur+1);}int main(){    while(~scanf("%d %d", &n, &k)){        if(n == -1 && k == -1)  break;        for(int i = 0;i < n;i++){            scanf("%s", map[i]);        }        m = 0;        ans = 0;        memset(book,0,sizeof(book));        dfs(0);        printf("%d\n", ans);    }    return 0;}

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