STL中的string

string相关的部分知识

string的定义

string str;
//定义并初始化
string str="abcd";

string数组的定义

const int maxn=1001;
string str[maxn];

string的加法

可以将两个string直接拼接起来

str3=str1+str2;//将str1和str2拼接，赋值给str3
str1+=str2;//将str2直接拼接到str1上

string的比较

直接使用==、！=、<=、<、>、>=比较大小，比较规则是字典序

string str1="aa",str2="aaa";
if(str1<str2)printf("ok");//输出了ok

string的长度

使用size()和length()函数，返回存放的字符数

string str="abcdxyz";
printf("%d %d\n",str.length(),str.length());

string中元素的删除

erase()有两种用法：删除单个元素、删除一个区间内的所有元素

这里只讲删除单个元素

erase(it)用于删除单个元素，it为需要删除的元素的迭代器

应用实例

1038 Recover the Smallest Number

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

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
const int maxn=10010;
string str[maxn];
bool cmp(string a,string b){
	return a+b<b+a;
}
int main(){
	int n;
	cin>>n;
	for(int i=0;i<n;i++)
	cin>>str[i];
	sort(str,str+n,cmp);
	string ans;
	for(int i=0;i<n;i++)
	  ans+=str[i];
	while(ans.size()!=0&&ans[0]=='0')
	   ans.erase(ans.begin());
	if(ans.size()==0)cout<<0;
	else
	  cout<<ans;
}