c++STl.txt

// 高位 加减乘除  
#include<cstdio>
#include<cstring>
struct bign{
	int d[1000];
	int len;
	bign(){
		memset(d,0,sizeof(d));
		len =0;
	}
};
bign change(char str[]){
	bign a;
	a.len = strlen(str);
	for(int i=0;i<a.len;i++){
		a.d[i] = str[a.len - i -1] -'0';
	}
	return a;
}
bign  add(bign a,bign b){
	bign c;
	int carry =0;
	for(int i=0;i<a.len||i<b.len;i++){
		int temp = a.d[i] + b.d[i] +carry;
		c.d[c.len++] = temp %10;
		carry = temp / 10;
		 
	}
	if(carry !=0){
		c.d[c.len++] = carry;
	}
	return c;
}
bign sub(bign a,bign b){
	bign c;
	for(int i=0;i<a.len || i<b.len;i++){
		if(a.d[i] < b.d[i]){
			a.d[i+1]--;
			a.d[i]+=10;
		}
		c.d[c.len++] = a.d[i] - b.d[i];
	}
	while( c.len-1 >=1 && c.d[c.len-1] ==0){
		c.len--;//去除最高位的0，同时至少保留一位最低位 
	}
	return c; 
}
bign muti(bign a,int b){
	bign c;
	int carry =0;
	for(int i=0;i<a.len;i++){
		int  temp= a.d[i] * b + carry;
		c.d[c.len++] = temp %10;
		carry = temp /10;
	}
	while(carry !=0){
		c.d[c.len++] = carry %10;
		carry /=10;
	}
	return c;
}
bign divide(bign a,int b,int& r){
	bign c;
	c.len  = a.len;
	for(int i=a.len-1; i>=0;i--){
		r = r *10 +a.d[i];
		if( r <b) c.d[i] = 0;
		else{
			c.d[i] = r/b;
			r = r%b;
		} 
	}
	while( c.len -1 >=1 && c.d[c.len-1] == 0){
		c.len --;
	} 
	return c;
} 
void print(bign a){
	for(int i =a.len-1;i>=0;i--){
		printf("%d",a.d[i]);
	} 
}
int main(){
	char str1[10000],str2[1000];
	scanf("%s %s",&str1,str2);
	bign a = change(str1);
	bign b = change(str2);
	print(add(a,b));
	return 0;
}
c++ 迭代器 <vector>的使用
#include<cstdio>
#include<vector>
using namespace std;
int main(){
	vector<int> vi;
	for(int i=1;i<=5;i++){
		vi.push_back(i);
	}
	vector<int>::iterator it = vi.begin();
	for(int i=0;i<5;i++){
		printf(i ? " %d" : "%d", *(it+i));
	} 
	printf("\n\n");
	
	vi.pop_back();
	for(vector<int>::iterator it = vi.begin(); it !=vi.end();it++){
		printf("%d ",*it);
	}
	printf("\n\n");
	vi.insert(vi.begin() + 2,-1);
	vi.erase(vi.begin() +1);
	for(int i=0;i<vi.size();i++){
		printf("%d",vi[i]);
	}
	return 0;
} 

//pat a1060
#include<iostream>
#include<string>
#include<cstdio>
using namespace std;
	int n;
string deal(string s,int& e){
	int k=0;
	while(s.length() >0 &&s[0] == '0'){
		s.erase(s.begin());
	}
	if(s[0] == '.'){
		s.erase(s.begin());
		while(s.length() >0 && s[0] =='0'){
			s.erase(s.begin());
			e--;
		}
	}else{
		while(k<s.length() && s[k] !='.'){
			k++;e++;
		}
		if(k <s.length()){
			s.erase(s.begin() + k);
		}
	}
	if(s.length() == 0){
		e =0;
	}
	int num =0;
	k=0;
	string res;
	while( num < n){
		if( k <s.length()) res+=s[k++];
		else res +='0';
		num++; 
	} 
	return res;
}
int main(){
	string s1,s2,s3,s4;
	cin>>n>>s1>>s2;
	int e1=0,e2=0;
	s3 = deal(s1,e1);
	s4 = deal(s2,e2);
	if(s3 == s4 && e1 == e2){
		cout<<"YES 0."<<s3<<"*10^"<<e1<<endl;
	}else{
		cout<<"NO 0."<<s3<<"*10^"<<e1<<" 0."<<s4<<"*10^"<<e2<<endl;
	}
	return 0;
}
//#include<iostream>
#include<string>
#include<queue>
#include<stack>
#include<cstdio>
using namespace std; 
int main(){
	stack<int> st;
	if(st.empty() == true){
		printf("empty\n");
	}else{
		printf("not empty\n");
	}
	for(int i=1;i<=5;i++){
		st.push(i);
	}
	for(int i=1;i<=3;i++){
		st.pop();
	}
	if(st.empty() == true){
		printf("empty\n");
	}else{
		printf("not empty\n");
	}
	printf("%d\n", st.top() );
	return 0;
}