牛客oj 习题6.12数字阶梯求和(大数相加)&&习题6.13大整数的因子(大数相除)

本来想用java干掉的，结果java实在是不懂，那只好继续c++处理字符串了，反正也不难，就是有点烦。

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <stack>
#include <cctype>
#include <cmath>
#include <climits>
 
using namespace std;
 
const int MAXN = 1005;
const int INF = INT_MAX;

string Plus(string big, string small){
	int lenbig = big.size();
	int lensmall = small.size();
	int cur = lensmall - 1;
	bool carry = false;
	int i;
	for(i = lenbig-1; i >= 0; i--){
		int num = (big[i]-'0') + (small[cur]-'0');
		if(carry){
			num++;
			carry = false;
		}
		if(num >= 10){
			num %= 10;
			carry = true;
		}
		big[i] = num + '0';
		cur--;
		if(cur == -1) break;
	}
	i--;
	while(carry){
		int num = (big[i]-'0') + 1;
		carry = false;
		if(num >= 10){
			num %= 10;
			carry = true;
		}
		big[i] = num + '0';
		i--;
		if(i == -1) break;
	}
	if(i == -1) big.insert(0, 1, '1');
	return big; 
}

int main(){
 //   freopen("in.txt", "r", stdin);
    int a, n;
    while(~scanf("%d %d", &a, &n)){
    	string str, ans;
    	str.insert(0, n, (a+'0'));
    	ans = str;
    	//str.erase(0, 1);
    	while(str.size() != 1){
    		str.erase(0, 1);
    		ans = Plus(ans, str);
    		//cout << ans << " " << str << endl;
    	}
    	cout << ans << endl;
    }
    return 0;
}

大整数相除，也是字符串问题，秒杀之。

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
#include <vector>
#include <stack>
#include <cctype>
#include <cmath>
#include <climits>
 
using namespace std;
 
const int MAXN = 1005;
const int INF = INT_MAX;

bool ZhengChu(string str, int x){
	int len = str.size();
	int remainder = 0;
	for(int i = 0; i < len; i++){
		int num = remainder*10 + (str[i] - '0');
		remainder = num%x;//只需保留余数即可 
	}
	if(remainder == 0) return true;
	else return false; 
}

int main(){
   // freopen("in.txt", "r", stdin);
    string c;
    while(cin >> c){
    	if(c == "-1") break;
    	vector<int> ans;
    	bool flag = false;
    	for(int i = 2; i <= 9; i++){
    		if(ZhengChu(c, i)){
    			flag = true;
    			ans.push_back(i);
    		}
    	}
    	if(flag){
    		bool tag = false;
    		for(int i = 0; i < ans.size(); i++){
    			if(tag) printf(" ");
    			tag = true;
    			printf("%d", ans[i]);
    		}
    		printf("\n");
    	}
    	else printf("none\n");
    }
    return 0;
}