HDU 1015 Safecracker(DFS）

题目链接

普通的DFS。。。输出字典序最大的。。。我竟然没注意。。

#include <stdio.h>
#include <string.h>
char p[31],o[31],max[31];
int k[31];
int ans,z,len;
void dfs(int step,int sum)
{
    int i;
    if(step == 5&&sum == ans)
    {
        z = 1;
        o[5] = '\0';
        if(strcmp(o,max) > 0)
        {
            strcpy(max,o);
        }
        return ;
    }
    if(step > 5)
    return ;
    for(i = 0;i <= len-1;i ++)
    {
        if(!k[i])
        {
            k[i] = 1;
            o[step] = p[i];
            if(step == 0)
            dfs(step+1,sum+p[i]-'A'+1);
            else if(step == 1)
            dfs(step+1,sum-(p[i]-'A'+1)*(p[i]-'A'+1));
            else if(step == 2)
            dfs(step+1,sum+(p[i]-'A'+1)*(p[i]-'A'+1)*(p[i]-'A'+1));
            else if(step == 3)
            dfs(step+1,sum-(p[i]-'A'+1)*(p[i]-'A'+1)*(p[i]-'A'+1)*(p[i]-'A'+1));
            else if(step == 4)
            dfs(step+1,sum+(p[i]-'A'+1)*(p[i]-'A'+1)*(p[i]-'A'+1)*(p[i]-'A'+1)*(p[i]-'A'+1));
            k[i] = 0;
        }
    }
    return ;
}
int main()
{
    int i,j;
    while(scanf("%d%s",&ans,p)!=EOF)
    {
        memset(o,0,sizeof(o));
        memset(k,0,sizeof(k));
        memset(max,0,sizeof(max));
        z = 0;
        len = strlen(p);
        if(ans == 0&&strcmp(p,"END") == 0)
        break;
        dfs(0,0);
        if(!z)
        printf("no solution\n");
        else
        printf("%s\n",max);
    }
    return 0;
}