• Codility---FrogRiverOne


    Task description

    A small frog wants to get to the other side of a river. The frog is initially located on one bank of the river (position 0) and wants to get to the opposite bank (position X+1). Leaves fall from a tree onto the surface of the river.

    You are given a zero-indexed array A consisting of N integers representing the falling leaves. A[K] represents the position where one leaf falls at time K, measured in seconds.

    The goal is to find the earliest time when the frog can jump to the other side of the river. The frog can cross only when leaves appear at every position across the river from 1 to X (that is, we want to find the earliest moment when all the positions from 1 to X are covered by leaves). You may assume that the speed of the current in the river is negligibly small, i.e. the leaves do not change their positions once they fall in the river.

    For example, you are given integer X = 5 and array A such that:

    A[0] = 1 A[1] = 3 A[2] = 1 A[3] = 4 A[4] = 2 A[5] = 3 A[6] = 5 A[7] = 4

    In second 6, a leaf falls into position 5. This is the earliest time when leaves appear in every position across the river.

    Write a function:

    class Solution { public int solution(int X, int[] A); }

    that, given a non-empty zero-indexed array A consisting of N integers and integer X, returns the earliest time when the frog can jump to the other side of the river.

    If the frog is never able to jump to the other side of the river, the function should return −1.

    For example, given X = 5 and array A such that:

    A[0] = 1 A[1] = 3 A[2] = 1 A[3] = 4 A[4] = 2 A[5] = 3 A[6] = 5 A[7] = 4

    the function should return 6, as explained above.

    Assume that:

    • N and X are integers within the range [1..100,000];
    • each element of array A is an integer within the range [1..X].

    Complexity:

    • expected worst-case time complexity is O(N);
    • expected worst-case space complexity is O(X), beyond input storage (not counting the storage required for input arguments).

    Elements of input arrays can be modified.

    Solution
     
    Programming language used: Java
    Total time used: 36 minutes
    Code: 13:14:04 UTC, java, final, score:  100
    // you can also use imports, for example:
    // import java.util.*;
    
    // you can write to stdout for debugging purposes, e.g.
    // System.out.println("this is a debug message");
    import java.util.Arrays;
    class Solution {
        public int solution(int X, int[] A) {
            // write your code in Java SE 8
            int count = 0;
            int [] res = new int[A.length];
            if(X > A.length)
                return -1;
            if(A.length ==1 && X == 1 && A[0] ==1)
                return 0;
            if(A.length ==1 && X == 1 && A[0] > 1)
                return -1;
            for(int i=0; i<A.length; i++) {
                if(A[i] <= X) {
                    if(res[A[i]-1] == 0) {
                        res[A[i]-1] = 1;
                        count++;
                    }
                    if(count == X) {
                        return i;
                    }
                }
            }
            return -1;
                    
        }
    }
  • 相关阅读:
    How to write an async method with out parameter?
    Common async / Task mistakes, and how to avoid them
    C# string reference type?
    Executing tasks in parallel
    SSIS How to Create an ETL Package Article 03/25/2022 3 minutes to read
    Should I worry about "This async method lacks 'await' operators and will run synchronously" warning
    C# 5.0 Async Tips and Tricks, Part 1
    What the async keyword actually does
    Why DataSet is being passed by reference without explicitly passing out or ref parameter? [duplicate]
    Windows权限维持
  • 原文地址:https://www.cnblogs.com/samo/p/6776985.html
Copyright © 2020-2023  润新知