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ZOJ 3768Continuous Login(找规律然后二分)
Pierre is recently obsessed with an online game. To encourage users to log in, this game will give users a continuous login reward. The mechanism of continuous login reward is as follows: If you have not logged in on a certain day, the reward of that day is 0, otherwise the reward is the previous day‘s plus 1.
On the other hand, Pierre is very fond of the number N. He wants to get exactly N points reward with the least possible interruption of continuous login.
Input
There are multiple test cases. The first line of input is an integer T indicates the number of test cases. For each test case:
There is one integer N (1 <= N <= 123456789).
Output
For each test case, output the days of continuous login, separated by a space.
This problem is special judged so any correct answer will be accepted.
Sample Input
4 20 19 6 9
Sample Output
4 4 3 4 2 3 2 3
Hint
20 = (1 + 2 + 3 + 4) + (1 + 2 + 3 + 4)
19 = (1 + 2 + 3) + (1 + 2 + 3 + 4) + (1 + 2)
6 = (1 + 2 + 3)
9 = (1 + 2) + (1 + 2 + 3)
Some problem has a simple, fast and correct solution.
Author: ZHOU, Yuchen
Source: The 14th Zhejiang University Programming Contest
#include<iostream> #include<cstdio> #include<cmath> #include<cstring> #include<string> #include<algorithm> #define ll long long using namespace std; int dp[20005]; int len; int erfen(int x) { int l=1,r=len; int mid; mid=(l+r)>>1; while(r>l) { if(dp[mid]==x) return mid; if(dp[mid]<x) l=mid+1; else r=mid-1; mid=(l+r)>>1; } if(dp[l]>x) l--; return l; } int main() { int i; dp[0]=0; dp[1]=1; for(i=1;i<=20000;i++) { dp[i]=dp[i-1]+i; if(dp[i]>=123456789) break; } len=i; int tes,n; cin>>tes; int a,b,c; while(tes--) { cin>>n; int p=erfen(n); if(dp[p]==n) { printf("%d\n",p); continue; } int flag=0; for(a=p;a>=1;a--) { b=erfen(n-dp[a]); if(dp[b]+dp[a]==n) { flag=1; break; } } if(flag) { printf("%d %d\n",a,b); continue; } flag=0; for(a=p;a>=1;a--) { int s=erfen(n-dp[a]); for(b=s;b>=1;b--) { c=erfen(n-dp[a]-dp[b]); if(dp[a]+dp[b]+dp[c]==n) { flag=1; break; } } if(flag) break; } if(flag) { printf("%d %d %d\n",a,b,c); continue; } } }