牛客网 2018校招真题 美团点评 K的倍数

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Description

牛客网 2018校招真题 K的倍数

Solving Ideas

sum[i + 1]: 表示序列p[0]...p[i]的和
从长度最大的子串开始判断，当剩余需要判断子串长度不可能大于已得最优解时，终止循环。

Solution

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * @author wylu
 */
public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        int[] p = new int[n];
        String[] strs = br.readLine().split(" ");
        for (int i = 0; i < n; i++) {
            p[i] = Integer.parseInt(strs[i]);
        }
        int k = Integer.parseInt(br.readLine());

        //sum[i + 1]: 序列p[0]...p[i]的和
        long[] sum = new long[n + 1];
        for (int i = 0; i < n; i++) sum[i + 1] = sum[i] + p[i];

        int res = 0;
        for (int i = n; i >= 1; i--) {
            for (int j = 0; j < i; j++) {
                if ((sum[i] - sum[j]) % k == 0) {
                    res = Math.max(res, i - j);
                    break;
                }
            }
            if (res >= i - 1) break;
        }
        System.out.println(res);
    }
}