题解 | #Primary Arithmetic#

#include<stdio.h>
#include<string.h>
int main() {
    int i, j, A[20], B[20];
    char S1[20], S2[20];
    scanf("%s %s", S1, S2);

    for (i = 0; i < 20; i++)A[i] = B[i] = 0;
    int len1 = strlen(S1), len2 = strlen(S2), cnt = 0;
    for (i = len1 - 1; i >= 0; i--)
        A[20 - len1 + i] = S1[i] - '0';
    for (i = len2 - 1; i >= 0; i--)B[20 - len2 + i] = S2[i] - '0';
    for (i = 0; i < 20; i++)A[i] += B[i];
    for (j = 19; j > 0; j--) {
        if (A[j] >= 10) {
            A[j - 1] += A[j] / 10;
            A[j] %= 10;
            cnt++;
        }
    }
    if (cnt == 1)printf("1 carry operation.\n");
    else if(cnt!=0)printf("%d carry operations.\n",cnt);
    else printf("NO carry operation.\n");
    return 0;
}