1 Source Code
 2 Problem: 2891        User: sdfzyhy
 3 Memory: 676K        Time: 0MS
 4 Language: G++        Result: Accepted
 5 
 6     Source Code
 7 
 8     //POJ 2891
 9     #include<vector>
10     #include<cstdio>
11     #include<cstring>
12     #include<cstdlib>
13     #include<iostream>
14     #include<algorithm>
15     #define rep(i,n) for(int i=0;i<n;++i)
16     #define F(i,j,n) for(int i=j;i<=n;++i)
17     #define D(i,j,n) for(int i=j;i>=n;--i)
18     using namespace std;
19     typedef long long LL;
20     inline LL getLL(){
21         LL r=1,v=0; char ch=getchar();
22         for(;!isdigit(ch);ch=getchar()) if(ch==‘-‘)r=-1;
23         for(; isdigit(ch);ch=getchar()) v=v*10+ch-‘0‘;
24         return r*v;
25     }
26     const int N=1e5+10,INF=~0u>>2;
27     /******************template*********************/
28     LL a[N],r[N],n;
29     void exgcd(LL a,LL b,LL &d,LL &x,LL &y){
30         if (!b){d=a;x=1;y=0;}
31         else{ exgcd(b,a%b,d,y,x);y-=(a/b)*x;}
32     }
33     LL ex_CRT(LL *m,LL *r,int n){
34         LL M=m[1],R=r[1],x,y,d;
35         F(i,2,n){
36             exgcd(M,m[i],d,x,y);
37             if ((r[i]-R)%d) return -1;
38             x = (r[i] - R) / d * x % (m[i] / d);
39             R += x * M;
40             M = M / d * m[i];
41             R %= M;
42         }
43         return R > 0 ? R :R + M;
44     }
45     int main(){
46     #ifndef ONLINE_JUDGE
47         freopen("2891.in","r",stdin);
48         freopen("2891.out","w",stdout);
49     #endif
50         while(scanf("%lld",&n)!=EOF){
51             F(i,1,n) a[i]=getLL(),r[i]=getLL();
52             printf("%lld\n",ex_CRT(a,r,n));
53         }
54         return 0;
55     }