【Codeforces Global Round 1 E】Magic Stones

【链接】 我是链接,点我呀:)
【题意】

你可以把c[i]改成c[i+1]+c[i-1]-c[i]
(2<=i<=n-1)
问你能不能把每一个c[i]都换成对应的t[i];

【题解】

            d[i] = c[i+1]-c[i]; (1<=i<=n-1)

            change c[i]

            c[i]' = c[i+1]+c[i-1]-c[i];

            d[i-1] = c[i]'-c[i-1];
                   = c[i+1]+c[i-1]-c[i]-c[i-1] == c[i+1]-c[i] = d[i];

            d[i] = c[i+1]-c[i]'
                 = c[i+1]-c[i+1]-c[i-1]+c[i]
                 = c[i] - c[i-1];
                 = d[i-1];
    也就是说对2..n-1进行操作的话
    就是把相邻的d的值交换一下
        显然这样的交换能让d变成任意顺序
    因此,只要c[1]==d[1]并且c[n]==d[n]
    然后排序后的c和排序后的d相同的话,就ok.
   这里必须要用Integer的equals方法比较才不会超时。。
   直接用int的a[i]!=b[i]会超时>_<

【代码】

import java.io.*;
import java.util.*;

//code start from here
/*
    d[i] = c[i+1]-c[i]; (1<=i<=n-1)

    change c[i]

    c[i]' = c[i+1]+c[i-1]-c[i];

    d[i-1] = c[i]'-c[i-1];
           = c[i+1]+c[i-1]-c[i]-c[i-1] == c[i+1]-c[i] = d[i];

    d[i] = c[i+1]-c[i]'
         = c[i+1]-c[i+1]-c[i-1]+c[i]
         = c[i] - c[i-1];
         = d[i-1];
 */

public class Main {

    final static int N = (int)1e5;
    static InputReader in;
    static PrintWriter out;
    static int n;
    static Integer c[],t[],d1[],d2[];

    public static void main(String[] args) throws IOException{
        in = new InputReader();
        //out = new PrintWriter(System.out);
        c = new Integer[N+10];t = new Integer[N+10];
        d1 = new Integer[N+10]; d2 = new Integer[N+10];

        n = in.nextInt();
        for (int i = 1;i <= n;i++) c[i] = in.nextInt();
        for (int i = 1;i <= n;i++) t[i] = in.nextInt();
        if (!c[1].equals(t[1]) || !c[n].equals(t[n])){
            System.out.println("No");
            return;
        }
        for (int i = 1;i <= n-1;i++) d1[i] = c[i+1]-c[i];
        for (int i = 1;i <= n-1;i++) d2[i] = t[i+1]-t[i];
        Arrays.sort(d1, 1,n);
        Arrays.sort(d2, 1,n);
        for (int i = 1;i <= n-1;i++)
            if (!d1[i].equals(d2[i])) {
                System.out.println("No");
                return;
            }
        System.out.println("Yes");
    }

    static class InputReader{
        public BufferedReader br;
        public StringTokenizer tokenizer;

        public InputReader() {
            br = new BufferedReader(new InputStreamReader(System.in),32768);
            tokenizer = null;
        }

        public String next(){
            while (tokenizer==null || !tokenizer.hasMoreTokens()) {
                try {
                tokenizer = new StringTokenizer(br.readLine());
                }catch(IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }
    }
}

原文地址：https://www.cnblogs.com/AWCXV/p/10357682.html