TLE csu 1236: 删数游戏

直接做，ＴＬＥ：

/* csu 1236 */
# include <stdio.h>
# include <string.h>
# define MAXN 2001
void del(char *s, int len)
{
    int i;
 
    i = 1;
    while (i < len && s[i-1]<=s[i])
        ++i;
    while (i < len)
    {
        s[i-1] = s[i];
        ++i;
    }
    s[i-1] = '\0';
}
int main()
{
    int len, i, S;
    char ch[MAXN];
 
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
 
    while (~scanf("%s%d", ch, &S))
    {
        len = strlen(ch);
        for (i = 0; i < S; ++i)
            del(ch, len);
        printf("%s\n", ch);
    }
 
    return 0;
}

改为标记，省去了元素移位，还是TLE，果断要换思路了。。水了这么久，该学学方法了

/* csu 1236 */
# include <stdio.h>
# include <string.h>
# define MAXN 2001
# define INDEX(i) ((i)>>3)
# define OFFSET(i) ((i)%8)
# define get_bit(i) ((m[INDEX(i)]>>OFFSET(i)) & 0x1)
# define set_bit(i) ((m[INDEX(i)]) |= (1<<OFFSET(i)))

char m[INDEX(MAXN)+1];

void mark(char *s, int len)
{
    int i;
    i = 0;
    while (i < len-1)
    {
        if (s[i]>s[i+1] && !get_bit(i)) break;
        ++i;
    }
    set_bit(i);
}

int main()
{
    int len, i, S;
    char ch[MAXN];

    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);

    while (~scanf("%s%d", ch, &S))
    {
        len = strlen(ch);
        for (i = 0; i < S; ++i)
            mark(ch, len);
        for (i = 0; i < len; ++i)
            if (!get_bit(i)) putchar(ch[i]);
        putchar('\n');
    }

    return 0;
}