HDU 3925 Substring 【大数相减】

//#pragma comment(linker, "/STACK:16777216") //for c++ Compiler
#include <stdio.h>
#include <iostream>
#include <fstream>
#include <cstring>
#include <cmath>
#include <stack>
#include <string>
#include <map>
#include <queue>
#include <vector>
#include <algorithm>
#define LL long long
#define Max(a,b) (((a) > (b)) ? (a) : (b))
#define Min(a,b) (((a) < (b)) ? (a) : (b))
#define Abs(x) (((x) > 0) ? (x) : (-(x)))
#define MOD 1000000007

using namespace std;

string Plus(string s1,string s2){
     if(s1.length() < s2.length()){
          string temp = s1;
          s1 = s2;
          s2 = temp;
     }
     for(int i = s1.length() - 1, j = s2.length() - 1; i >= 0; --i, --j){
          s1[i] = char(s1[i] + (j >= 0 ? s2[j]- ‘0‘ : 0));
          if(s1[i] - ‘0‘ >= 10){
              s1[i] = char((s1[i] - ‘0‘) % 10 + ‘0‘);
              if(i) ++s1[i-1];
              else  s1 += ‘1‘;
          }
     }
     return s1;
}

string Minus(string a,string b){
    string c="",ans="",t;
    int flag = 0, k = 0;  
    bool flag2 = false; 
    if(a.length() < b.length() || (a.length() == b.length()&& a.compare(b) < 0)){ 
        t = a;
        a = b;
        b = t;
        flag2 = true;
    }
    int i = a.length() - 1, j = b.length() - 1;
    while(i >= 0 && j >= 0){
        if(a[i] + flag > b[j]){
          c += a[i] + flag - b[j] + ‘0‘;
          flag = 0;
        }
        else if(a[i] + flag == b[j]){
          c += ‘0‘;
          flag = 0;
        }
        else{
          c += (a[i] - ‘0‘) + flag + 10 - (b[j] - ‘0‘) + ‘0‘;
          flag = -1;
        }
        --i;
        --j;
        ++k;
    }
    while(i >= 0){
        if(a[i] + flag < ‘0‘){
            c += a[i] + flag + 10 + ‘0‘;
            flag = -1;
        }
        else{
            c += a[i] + flag;
            flag = 0;
        }
        --i;
        ++k;
    }
    int len = k - 1;
    while(c[len] == ‘0‘ && len > 0) --len;
    for(j = 0; j <= len; ++j)
      ans += c[j];
    if(flag2){ 
        ans += ‘-‘;
    }
    char tt;
    for(i = 0, j = ans.length()-1; i < j; ++i, --j){
        tt = ans[i]; 
        ans[i] = ans[j];
        ans[j] = tt;
    }
    return ans;
}

bool judge(string a, string b){
    if(a.size() < b.size()) return false;
    else if(a.size() > b.size())    return true;
    else{
        for(int i = 0; i < a.size(); ++i){
            if(a[i] > b[i]) return true;
            else if(a[i] < b[i]) return false;
        }
    }
}

int main(){
    int i, j, t, n, m, numCase = 0;
    string s1,s2, hh;
    string cnt, ans;
    bool flag1;
    scanf("%d",&t);
    while(t--){
        cin >> s1 >> s2;
        flag1 = false;
        int len1 = s1.size();
        int len2 = s2.size();
        if(judge(s2, s1)){
            cout << "Case #" << ++numCase << ": " << Minus(s2, s1) << endl;
            continue;
        }
        for(i = 0; i < len1 - len2; ++i){
            string ww = s1.substr(i, len2);
            if(ww.compare(s2) == 0){
                flag1 = true;
                break;
            }
        }
        if(flag1){
            cout << "Case #" << ++numCase << ": " << ‘0‘ << endl;
            continue;
        }
        for(i = 0; i < len1 - len2 + 2; ++i){
            if(i == len1 - len2 + 1){
                hh = s1.substr(len1 - len2 - i + 1, i + len2 - 1);
            } else{
                hh = s1.substr(len1 - len2 - i, i + len2);
            }
            if(judge(hh, s2)){
                string gg = "1";
                gg += s2;
                ans = Minus(gg ,hh);
            }
            else{
                ans = Minus(s2 ,hh);
            }
            s2 += "0";
            if(i == 0){
                cnt = ans;
            } else{
                if(judge(cnt, ans)){
                    cnt = ans;
                }
            }
        }
        cout << "Case #" << ++numCase << ": " << cnt << endl;
    }

    return 0;
}