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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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