E. Mahmoud and Ehab and the function Codeforces Round #435 (Div. 2)

http://codeforces.com/contest/862/problem/E

二分答案

一个数与数组中的哪个数最接近：

先对数组中的数排序，然后lower_bound

 #include <cstdio>
 #include <cstdlib>
 #include <cmath>
 #include <cstring>
 #include <time.h>
 #include <string>
 #include <set>
 #include <map>
 #include <list>
 #include <stack>
 #include <queue>
 #include <vector>
 #include <bitset>
 #include <ext/rope>
 #include <algorithm>
 #include <iostream>
 using namespace std;
 #define ll long long
 #define minv 1e-6
 #define inf 1e18
 #define pi 3.1415926536
 #define E  2.7182818284
 const ll mod=1e9+;//
 const int maxn=1e5+;

 ll b[maxn],f[maxn];

 int main()
 {
     int n,m,q,g=,i,l,r;
     ll a,tot=,sum=,v;
     scanf("%d%d%d",&n,&m,&q);
     for (i=;i<=n;i++)
     {
         scanf("%lld",&a);
         if (i & )
             sum+=a;
         else
             sum-=a;
     }
     for (i=;i<=m;i++)
     {
         scanf("%lld",&b[i]);
         if (i & )
             tot+=b[i];
         else
             tot-=b[i];
         if (i>=n)
         {
             g++;
             if ((i-n) & )
                 f[g]=-tot;
             else
                 f[g]=tot;
             if ((i-n+) & )
                 tot-=b[i-n+];
             else
                 tot+=b[i-n+];
         }
     }
     sort(f+,f+g+);

         i=lower_bound(f+,f+g+,sum)-f;
         v=inf;
         if (i->= && i-<=g)
             v=min(v,abs(sum-f[i-]));
         if (i>= && i<=g)
             v=min(v,abs(sum-f[i]));
         if (i+>= && i+<=g)
             v=min(v,abs(sum-f[i+]));
         printf("%lld\n",v);

     while (q--)
     {
         scanf("%d%d%lld",&l,&r,&a);
         if ((r-l)%==)
         {
             if (l & )
                 sum+=a;
             else
                 sum-=a;
         }

         i=lower_bound(f+,f+g+,sum)-f;
         v=inf;
         if (i->= && i-<=g)
             v=min(v,abs(sum-f[i-]));
         if (i>= && i<=g)
             v=min(v,abs(sum-f[i]));
         if (i+>= && i+<=g)
             v=min(v,abs(sum-f[i+]));
         printf("%lld\n",v);
     }
     return ;
 }