Thanos Sort

题目链接：http://codeforces.com/contest/1145/problem/A

愚人节题目，求最长不下降连续序列，序列还得是去一半，去一半得到的。

递归

import java.util.Scanner;

public class pro1145A {

    public static int rise(int[] R,int ind,int len){
        if(len==1) return 1;
        boolean flag = true;
        for(int i=ind;i<ind+len-1;++i){
            if(R[i]>R[i+1]){
                flag = false;
                break;
            }
        }
        if(flag)
            return len;
        else{
            return Math.max(rise(R,ind,len/2),rise(R,ind+len/2,len/2));
        }
    }

    public static void main(String[] args){
        Scanner input = new Scanner(System.in);

        int N;
        N = input.nextInt();

        int[] raw = new int[N];
        for(int i=0;i<N;++i){
            raw[i] = input.nextInt();
        }

        int ans = rise(raw,0,N);
        System.out.println(ans);
    }
}

分治

package com.jetbrains;

import java.util.Scanner;

public class pro1145A {

    public static int rise(int[] arr,int L,int R){
        if(L + 1 == R) return 1;

        int mid = L+(R-L)/2;
        int Lans = rise(arr,L,mid),
            Rans = rise(arr,mid,R);

        if(arr[mid-1] <= arr[mid]&& Lans == mid-L
                && Rans == R-mid)
            return  Lans+Rans;
        else
            return Math.max(Lans,Rans);
    }

    public static void main(String[] args){
        Scanner input = new Scanner(System.in);

        int N;
        N = input.nextInt();

        int[] raw = new int[N];
        for(int i=0;i<N;++i){
            raw[i] = input.nextInt();
        }

        int ans = rise(raw,0,N);
        System.out.println(ans);
    }
}