FZU 2111 Min Number (想法题)

http://acm.fzu.edu.cn/problem.php?pid=2111

/*0ms,232KB*/

#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
const int mx = 1005;

char s[mx];
deque<int> pos[10];

int main()
{
	int t, n, m, i, maxpos, minval, beg;
	scanf("%d", &t);
	while (t--)
	{
		scanf("%s%d", s, &m);
		n = strlen(s);
		if (m)
		{
			///注意s没有前导0
			for (i = 0; i < 10; ++i) pos[i].clear();
			for (i = 0; i < n; ++i) pos[s[i] & 15].push_back(i);
			///先把开头的那个数尽量换小，但不能用0换
			for (i = 1; i < (s[0] & 15); ++i)
			{
				if (pos[i].size())
				{
					swap(s[0], s[pos[i].back()]);
					--m;
					break;
				}
			}
			///然后就按一般的思路交换了
			for (beg = 1; beg <= m; ++beg)
			{
				maxpos = 0, minval = 10;
				for (i = n - 1; i > beg; --i)
				{
					if ((s[i] & 15) < minval)
					{
						minval = s[i] & 15;
						maxpos = i;
					}
				}
				for (i = beg; i < maxpos; ++i)
				{
					if ((s[i] & 15) > minval)
					{
						swap(s[i], s[maxpos]);
						break;
					}
				}
				if (i == maxpos) ++m;
			}
		}
		puts(s);
	}
	return 0;
}