2018hdu杭電多校第五場 hdu6351 Beautiful Now(暴力全排列)
Beautiful Now
Time Limit: 5000/2500 MS (Java/Others) Memory Limit: 262144/262144 K (Java/Others)
Total Submission(s): 1677 Accepted Submission(s): 621
Problem Description
Anton has a positive integer n, however, it quite looks like a mess, so he wants to make it beautiful after k swaps of digits.
Let the decimal representation of n as (
Could you please tell him the minimum integer and the maximum integer he can obtain after k swaps?
Input
The first line contains one integer T, indicating the number of test cases.
Each of the following T lines describes a test case and contains two space-separated integers n and k.
1≤T≤100, 1≤n,k≤
Output
For each test case, print in one line the minimum integer and the maximum integer which are separated by one space.
Sample Input
5
12 1
213 2
998244353 1
998244353 2
998244353 3
Sample Output
12 21
123 321
298944353 998544323
238944359 998544332
233944859 998544332
題意:給你一個數字n(1<=n<=1e9),通過k次交換其中的數字使其達到最小和最大。
題解:這題不是貪心!!! 看了題解後發現是暴搜(其實2500ms的時間限制已經暗示了),用next_permutation 和 記錄一下位置 記得要剪一下枝
程式碼:
#include <bits/stdc++.h>
using namespace std;
#define rep(i,s,e) for(int i=s;i<e;++i)
#define per(i,s,e) for(int i=e-1;i>=s;--i)
#define INF 0x3f3f3f3f
#define mem(a,x) memset(a, x, sizeof(a))
const int N = 15;
char s[N];
int ans = 0, _, maxx, minn, k, q[N], q1[N], c[N], p[N];
void solve() {
int len = strlen(s+1), cnt;
do {
if (c[p[1]] == 0) continue; // 前導0
rep (i, 1, len+1) q[i] = p[i]; //q陣列記錄全排列後的位置
ans = cnt = 0;
rep (i, 1, len+1) {
ans = ans * 10 + c[p[i]];
if (q[i] != i) {
rep (j, i+1, len+1) {
if (q[j] == i) {
swap(q[i], q[j]);
cnt++;
if (cnt > k) goto nxt;
break;
}
}
}
}
nxt: if (cnt > k) continue;
maxx = max(maxx, ans);
minn = min(minn, ans);
} while (next_permutation(p+1, p+len+1));
}
int main() {
for (scanf("%d", &_); _; --_) {
mem(q, 0);
mem(q1, 0);
maxx = -INF;
minn = INF;
scanf("%s%d", s+1, &k);
int len = strlen(s+1);
rep (i, 1, len+1) {
c[i] = s[i] - '0'; // 把數字轉成int陣列
q[c[i]]++; // 用類似桶排序的方法
q1[c[i]]++; // 將i大小出現的次數存在q[i]和q1[i]中
}
if (k >= len-1) { //(剪枝) len-1次就可以直接輸出最優的最小值和最大值
// 最小值
rep (i, 1, 10) { //首位
if (q[i]) {
printf("%d", i);
q[i]--;
break;
}
}
rep (i, 0, 10) {
while (q[i]) {
printf("%d", i);
q[i]--;
}
}
printf(" ");
// 最大值
per (i, 0, 10) {
while (q1[i]) {
printf("%d", i);
q1[i]--;
}
}
puts("");
continue;
}
rep (i, 1, len+1) p[i] = i;
solve();
printf("%d %d\n", minn, maxx);
}
}