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/**
* Description: For generating random numbers.
*
* @ Author Create/Modi Note
* Xiaofeng Xie Feb 22, 2001
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* Please acknowledge the author(s) if you use this code in any way.
*
* @version 1.0
* @Since MAOS1.0
*/
package net.adaptivebox.global;
public class RandomGenerator {
/**
* This function returns a random integer number between the lowLimit and
* upLimit.
*
* @param lowLimit
* lower limits upLimit The upper limits (between which the
* random number is to be generated)
* @return int return value Example: for find [0,1,2]
*/
public static int intRangeRandom(int lowLimit, int upLimit) {
int num = (int) Math
.floor(doubleRangeRandom(lowLimit, upLimit + 1) - 1E-10);
return (num);
}
/**
* This function returns a random float number between the lowLimit and
* upLimit.
*
* @param lowLimit
* lower limits upLimit The upper limits (between which the
* random number is to be generated)
* @return double return value
*/
public static double doubleRangeRandom(double lowLimit, double upLimit) {
double num = lowLimit + Math.random() * (upLimit - lowLimit);
return (num);
}
public static int[] randomSelection(int maxNum, int times) {
if (times <= 0)
return new int[0];
int realTimes = Math.min(maxNum, times);
boolean[] flags = new boolean[maxNum];
boolean isBelowHalf = times < maxNum * 0.5;
int virtualTimes = realTimes;
if (!isBelowHalf) {
virtualTimes = maxNum - realTimes;
}
int i = 0;
int upper = maxNum - 1;
int[] indices = new int[realTimes];
while (i < virtualTimes) {
indices[i] = intRangeRandom(0, upper);
if (!flags[indices[i]]) {
flags[indices[i]] = true;
i++;
}
}
if (!isBelowHalf) {
int j = 0;
for (i = 0; i < maxNum; i++) {
if (flags[i] == isBelowHalf) {
indices[j] = i;
j++;
if (j == realTimes)
break;
}
}
}
return indices;
}
}
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