URAL-1998 The old Padawan 二分

　　题目链接：http://acm.timus.ru/problem.aspx?space=1&num=1998

　　题意：有n个石头，每个石头有个重量，每个时间点你能让一个石头飞起来，但有m个时间点，你会分心，使得已经飞起来的石头会有重量之和大于k的石头掉下来，问你最终使的所有石头飞起来的时间。

　　维护一个前缀和，然后二分就可以了。

  1 //STATUS:C++_AC_93MS_1113KB
  2 #include <functional>
  3 #include <algorithm>
  4 #include <iostream>
  5 //#include <ext/rope>
  6 #include <fstream>
  7 #include <sstream>
  8 #include <iomanip>
  9 #include <numeric>
 10 #include <cstring>
 11 #include <cassert>
 12 #include <cstdio>
 13 #include <string>
 14 #include <vector>
 15 #include <bitset>
 16 #include <queue>
 17 #include <stack>
 18 #include <cmath>
 19 #include <ctime>
 20 #include <list>
 21 #include <set>
 22 #include <map>
 23 using namespace std;
 24 //#pragma comment(linker,"/STACK:102400000,102400000")
 25 //using namespace __gnu_cxx;
 26 //define
 27 #define pii pair<int,int>
 28 #define mem(a,b) memset(a,b,sizeof(a))
 29 #define lson l,mid,rt<<1
 30 #define rson mid+1,r,rt<<1|1
 31 #define PI acos(-1.0)
 32 //typedef
 33 typedef __int64 LL;
 34 typedef unsigned __int64 ULL;
 35 //const
 36 const int N=100010;
 37 const int INF=0x3f3f3f3f;
 38 const int MOD=95041567,STA=8000010;
 39 const LL LNF=1LL<<60;
 40 const double EPS=1e-8;
 41 const double OO=1e15;
 42 const int dx[4]={-1,0,1,0};
 43 const int dy[4]={0,1,0,-1};
 44 const int day[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
 45 //Daily Use ...
 46 inline int sign(double x){return (x>EPS)-(x<-EPS);}
 47 template<class T> T gcd(T a,T b){return b?gcd(b,a%b):a;}
 48 template<class T> T lcm(T a,T b){return a/gcd(a,b)*b;}
 49 template<class T> inline T lcm(T a,T b,T d){return a/d*b;}
 50 template<class T> inline T Min(T a,T b){return a<b?a:b;}
 51 template<class T> inline T Max(T a,T b){return a>b?a:b;}
 52 template<class T> inline T Min(T a,T b,T c){return min(min(a, b),c);}
 53 template<class T> inline T Max(T a,T b,T c){return max(max(a, b),c);}
 54 template<class T> inline T Min(T a,T b,T c,T d){return min(min(a, b),min(c,d));}
 55 template<class T> inline T Max(T a,T b,T c,T d){return max(max(a, b),max(c,d));}
 56 //End
 57 
 58 int t[N],sum[N];
 59 int n,m,k;
 60 
 61 int binary(int l,int r,LL tar)
 62 {
 63     int mid;
 64     while(l<r){
 65         mid=(l+r)>>1;
 66         if(sum[mid]<tar)l=mid+1;
 67         else r=mid;
 68     }
 69     return l;
 70 }
 71 
 72 int main()
 73 {
 74  //   freopen("in.txt","r",stdin);
 75     int i,j,a,w,ans;
 76     while(~scanf("%d%d%d",&n,&m,&k))
 77     {
 78         for(i=1;i<=n;i++){
 79             scanf("%d",&a);
 80             sum[i]=sum[i-1]+a;
 81         }
 82         for(i=1;i<=m;i++)
 83             scanf("%d",&t[i]);
 84         w=ans=0;
 85         for(i=1;i<=m;i++){
 86             w+=t[i]-t[i-1]-1;
 87             if(w>=n){
 88                 ans+=n-(w-(t[i]-t[i-1]-1));
 89                 break;
 90             }
 91             ans=t[i];
 92             w=binary(1,w+1,sum[w]-k)-1;
 93         }
 94         if(w<n){
 95             ans+=n-w;
 96         }
 97 
 98         printf("%d\n",ans);
 99     }
100     return 0;
101 }