算法笔记-----大整数相＋－-----数组---效率

//
// Created by alim on 2017/12/23.
//


#include <stdlib.h>
#include <cstring>
#include <iostream>
using namespace std;

#define M 100

char sa[1000];
char sb[1000];

typedef struct _Node{
    int s[M];//数字
    int l;//数字长度
}Node,*pNode;


void dzs_add(pNode pa,pNode pb,pNode result){
    int i, cc;
    pNode temp;

    if (pa->l < pb->l) {
        temp = pb;
        pb = pa;
        pa = temp;
    }

    for (int j = 0; j < pa->l; ++j) {
        result->s[j] = pa->s[j];
    }
    result->l = pa->l;

    cc = 0;
    for (i = 0; i < pb->l; ++i) {
        result->s[i] = (pa->s[i] + pb->s[i] + cc) % 10;
        cc = (pa->s[i] + pb->s[i]) / 10;
    }
    if (cc != 0) {
        result->s[i] = result->s[i]+cc;
    }
    if (i >= result->l) {
        result->l = i+1;
    }

    return;
}

void dzs_jian(pNode pa,pNode pb,pNode result){
    int i, cc;
    pNode temp;

    if (pa->l < pb->l) {
        temp = pb;
        pb = pa;
        pa = temp;
    }
    for (int j = 0; j < pa->l; ++j) {
        result->s[j] = pa->s[j];
    }
    result->l = pa->l;
    cc = 0;
    for (i = 0; i < pb->l; ++i) {
        if (pa->s[i] >= pb->s[i]) {
            result->s[i] = pa->s[i] - pb->s[i];
        } else {
            result->s[i + 1] -= 1;
            result->s[i] = pa->s[i] + 10 - pb->s[i];
        }
    }
    if (i >= result->l) {
        result->l = i+1;
    }
}
int main() {
    Node ans,a,b;
    cout << "请输入大整数 a："<<endl;
    cin >> sa;
    cout << "请输入大整数 b：" << endl;
    cin >> sb;
    a.l = strlen(sa);//以字符串进行处理，计算长度
    b.l = strlen(sb);

    //倒向存储
    int z=0,i;
    for (int i = a.l-1; i >= 0; i--) {
        a.s[z++] = sa[i]-'0';
    }

    z=0;
    for (int i = b.l-1; i >= 0; i--) {
        b.s[z++] = sb[i] - '0';
    }
//    dzs_add(&a, &b, &ans);
    dzs_jian(&a, &b, &ans);
    cout << "最终结果为：
";
    for (i = ans.l-1; i >= 0; i--) {
        cout<<ans.s[i];
    }

    cout << endl;
    return 0;
}