[英]Java 2D array assigning randomly
我有一個數組a [5] [5]和幾個值。 我想根據我創建的隨機百分比隨機分配值。 例如,一個值是6,數組中25%的元素應具有值6。到目前為止,我已經做到了:我創建了隨機百分比,並且能夠為數組中的不同元素隨機分配值。 我的問題是:超過25%的元素具有6。我的問題是:如何確保在給元素分配6時,數組a [5] [5]中恰好25%的元素具有該值? 我是編程新手,嘗試了幾次循環和ifs,但沒有任何結果適合我。 請把我推向正確的方向。
25的25%約為6。這是不正確的。 這是一個可能的解決方案。
import java.util.Random;
import java.util.Scanner;
public class Matrix25 {
public static void main(String[] args) {
int[][] Matrix = new int[5][5];
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the number you want to fill the array to 25%: ");
int number = scanner.nextInt();
int percentage=25;
generateMatrix(Matrix,number,percentage);
printMatrix(Matrix);
}
public static void generateMatrix(int Matrix[][],int num, int perc) {
int n;
int max=Matrix.length*Matrix[0].length;
int[] numbers = new int[max];
Random rnd = new Random();
int m = (int)(max * (perc/100.0));
int x=num>m?m-1:m;
for(int i=0;i<max;i++)
numbers[i]=(i<x)?num:i+1;
for(int i=0;i<Matrix.length;i++)
for(int j=0;j<Matrix[i].length;j++) {
n=rnd.nextInt(max);
Matrix[i][j]=numbers[n];
numbers[n]=numbers[max-1];
max--;
}
}
public static void printMatrix(int Matrix[][]) {
for(int i=0;i<Matrix.length;i++) {
for(int j=0;j<Matrix[i].length;j++)
System.out.printf("%3d\t",Matrix[i][j]);
System.out.print("\n");
}
}
}
我會這樣
import java.util.Random;
import java.util.Scanner;
class Random2darray {
/**
* @param args
*/
public static void main(String[] args) {
// Create array; you specified 5x5 but you probably shouldn't hard code like this
int[][] numbers = new int[5][5];
//Create a scanner to get user input
Scanner scanner = new Scanner(System.in);
//I am not doing anything to make sure they give a decimal so the program won't work
//right if you are not giving a decimal
System.out.println("How much do you want to fill? Enter a decimal.");
//Get a double
double populatePercentage = scanner.nextDouble();
System.out.println("What number do you want to fill with?");
//Get an int
int fillNumber = scanner.nextInt();
//Don't hardcode like this
int fillTimes = numberOfTimesToFill(25, populatePercentage);
//This is declared outside of the loops because otherwise it will be
//reset each time the loop runs
int count = 0;
//Create a random number generator; default seed is current time which is good enough for this
Random rand = new Random();
//Fill the array with numbers
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 5; j++) {
//Check if you have filled with given number enough times
if(count < fillTimes){
numbers[i][j] = fillNumber;
//Increment count by 1; this is how you are keeping track
count++;
}else{
//Otherwise pick a random number generator
//This will pick a random int between 0 - 50 inclusive
int randomNumber = rand.nextInt(51);
//This will make sure that you are not generating random numbers that are the same
//as the number you are filling with; This says if it is the same generate a new number
while(randomNumber == fillNumber){
randomNumber = rand.nextInt(51);
}
//Once we know its random fill the spot in the array
numbers[i][j] = randomNumber;
}
}
}
//Print the array out
printArray(numbers);
}
private static void printArray(int[][] numbers) {
//Just loop through and print every number
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 5; j++) {
//Print with formatting: this says print a digit (%d) followed by a
//tab(\t) and then specifies what number I want to print
System.out.printf("%d\t", numbers[i][j]);
}
//Print a new line after each row
System.out.printf("\n");
}
}
private static int numberOfTimesToFill(int elements, double populatePercentage) {
System.out.println((int)(populatePercentage * elements));
//Cast to an int to truncate the decimal part of the number because you can't have
//a fraction of an element
return (int)(populatePercentage * elements);
}
}
我已經注釋了代碼以解釋所有操作。 但是,它不能防止用戶輸入錯誤,並且會對數組的大小進行硬編碼,因此應始終避免硬編碼。 在此示例中,我做了(並標記在哪里)以使其更加清晰。 另外,正如上面評論中提到的那樣,對於您所需要的25%中的25%的情況,這是不可能的。 這是因為.25 * 25 = 6.25,而元素不能有.25。
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