leetcode/MultiplyStrings.cpp at master · jiangshen95/leetcode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
#include<iostream>
#include<string.h>

using namespace std;

class Solution {
public:
    string multiply(string num1, string num2) {

        int flag=0;
        string res="";

        for(int i=num1.length()-1;i>=0;i--){

        	flag=0;
        	string onesum="";

        	for(int j=num2.length()-1;j>=0;j--){


        		int last;
        		last=(num1[i]-'0')*(num2[j]-'0');
        		last+=flag;
        		onesum+=last%10+'0';
        		flag=last/10;

			}

			if(flag>0){
				onesum+=flag+'0';
			}

			flag=0;
			int k;
			for(k=0;k<onesum.length()&&k+(num1.length()-i-1)<res.length();k++){

				int sum=(onesum[k]-'0')+(res[k+(num1.length()-i-1)]-'0')+flag;
				res[k+(num1.length()-i-1)]=sum%10+'0';
				flag=sum/10;

			}
			for(;k<onesum.length();k++){
				int sum=onesum[k]-'0'+flag;
				res+=sum%10+'0';
				flag=sum/10;
			}
			if(flag>0){
				res+=flag+'0';
			}

			cout<<res<<endl;

			system("pause");
		}

        for(int i=0;i<res.length()/2;i++){
        	char v=res[i];
        	res[i]=res[res.length()-i-1];
        	res[res.length()-i-1]=v;
		}

		if(res.length()<=0||res[0]=='0'){
			return "0";
		}

		return res;
    }
};

int main(){
	string num1,num2;
	cin>>num1;
	cin>>num2;

	Solution *solution=new Solution();
	cout<<solution->multiply(num1,num2);

	return 0;
}