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 }
