PAT A1038 Recover the Smallest Number (30 分)

Given a collection of number segments, you are supposed to recover the smallest number from them. For example, given { 32, 321, 3214, 0229, 87 }, we can recover many numbers such like 32-321-3214-0229-87 or 0229-32-87-321-3214 with respect to different orders of combinations of these segments, and the smallest number is 0229-321-3214-32-87.

Input Specification:

Each input file contains one test case. Each case gives a positive integer N (≤10​4​​) followed by N number segments. Each segment contains a non-negative integer of no more than 8 digits. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print the smallest number in one line. Notice that the first digit must not be zero.
Sample Input:

5 32 321 3214 0229 87

Sample Output:

22932132143287

实现思路

采用字符串大小拼接排序的方法，调用sort函数即可拼出最小的数，但是需要注意前导的0需要删除。

AC代码：

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;

bool cmp(string a,string b) {
	return (a+b)<(b+a);
}

int main() {
	string str;
	vector<string> sq;
	int n;
	cin>>n;
	while(n--) {
		cin>>str;
		sq.push_back(str);
	}
	sort(sq.begin(),sq.end(),cmp);
	string ans;
	for(int i=0; i<sq.size(); i++) {
		ans+=sq[i];
	}
	while(ans.size()>0&&ans[0]=='0') ans.erase(ans.begin());
	if(ans.size()>0) cout<<ans;
	else cout<<"0";
	return 0;
}