题目:求两个小于十亿的数,按位相乘再相加如12*45=1*4+1*5+2*4+2*5
法1:
#include<iostream>
#include<string.h>
using namespace std;
char a[10], b[10];
int main(){
while (cin >> a >> b)
{
int la = strlen(a);
int lb = strlen(b);
int res = 0;
for (int i = 0; i < la; i++)
for (int j = 0; j < lb; j++)
res += (a[i] - '0')*(b[j] - '0');
cout << res << endl;
}
return 0;
}
法2:
#include<iostream>
#include<string.h>
using namespace std;
int a[10], b[10];
int main(){
__int64 x, y;
while (cin >> x >> y)
{
int i = 0,j=0;
while (x)
{
a[i++] = x % 10;
x = x / 10;
}
while (y)
{
b[j++] = y % 10;
y = y / 10;
}
int res=0;
for (int c = 0; c < i; c++)
for (int d = 0; d < j; d++)
{
res += a[c] * b[d];
}
cout << res << endl;
}
return 0;
}