Daily code 300 lines learning notes day 10

1. Comprehensive use

Students' grades are stored in a matrix , Where the line represents the student , List the accounts . Such as ： The first 0 Line representation 0 A student's math 、 Chinese language and literature 、 English scores . requirement ：

1. Random generation of student scores , Interval is [50, 100].
2. Find the best 、 The worst classmate . But students who fail in the course will not participate in the evaluation .

2. Generation of random numbers

java.util.Random In bag , It can be used int nextInt(int n) , Returns a pseudo-random number , It is taken from the random number generator sequence 、 stay 0（ Include ） And the specified value （ barring ） Evenly distributed between int value .

Random number generation seems to have no range , If you want to generate a range of random numbers , The following format is often used ：

x=Arrays.nextInt( Maximum - minimum value )+ minimum value ;

3. Code segment

package demo3;

import java.util.Arrays;
import java.util.Random;

public class Task1 {
	public static void main(String[] args) {

		int n = 10;//  Number of students 
		int m = 4;//  Number of accounts 
		int lowerBound = 40;// Set minimum score 
		int upperBound = 100;// Maximum score 
		int thresholed = 60;// Pass grade threshold 
		// Random
		Random tempRandom = new Random();
		int[][] data = new int[n][m];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				data[i][j] = lowerBound + tempRandom.nextInt(upperBound - lowerBound);//  Generate 50-65 Random numbers in the range 
			}
		} // Random
		System.out.println("The data is:\r\n" + Arrays.deepToString(data));
		//  Calculate the total score , And will 60 The total score of less than points is converted into 0
		int[] totalScores = new int[n];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				if (data[i][j] < thresholed) {
					totalScores[i] = 0;
					break;
				} // Of if
				totalScores[i] += data[i][j];
			} // Of for j
		} // Of for i

		System.out.println("\rThe total scores are:\r\n" + Arrays.toString(totalScores));

		// Best and Worst
		int tempBestIndex = 100;
		int tempWorstIndex = 100;
		int tempBestScore = 0;
		int tempWorstScore = 100000;
		for (int i = 0; i < n; i++) {
			if (totalScores[i] == 0) {
				continue;
			} // of if
				//  Sort replace maximum , And reset i To indicate the best students 
			if (tempBestScore < totalScores[i]) {
				tempBestScore = totalScores[i];
				tempBestIndex = i;
			} // of if
				//  Sort replace minimum , And reset i To indicate the worst students 
			if (tempWorstScore > totalScores[i]) {
				tempWorstScore = totalScores[i];
				tempWorstIndex = i;
			} // of if

		} // of for
			//  Final output 
		if (tempBestIndex == -1) {
			System.out.println("Cannot find best student. All students have failed.");
		} else {
			System.out.println("\rThe best student is No." + tempBestIndex + " with scores: "
					+ Arrays.toString(data[tempBestIndex]));
		} // Of if

		if (tempWorstIndex == -1) {
			System.out.println("Cannot find worst student. All students have failed.");
		} else {
			System.out.println("The worst student is No." + tempWorstIndex + " with scores: "
					+ Arrays.toString(data[tempWorstIndex]));
		} // of else
	}// of main
}// of Task1

The final code running result ：

4. summary ：

In this code , At first, random numbers are generated for In circulation , take i and j The initial values of are all set to 1, This leads to randomly generated scores , Everyone's first subject has become 0 了 . Output the best result at the end , In the code segment with the worst score , Didn't notice the parentheses , Throw it to the front for In circulation , This leads to the output of several results in the cycle .