基尼系数
基尼系数=差值综合/(2人数财富总和) 【注意：】因为基尼系数是0-1的小数所以使用double
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public static void main(String [] args){
int n=100;
int t = 1000000000;
System.out.println("人数："+n);
System.out.println("轮数："+t);
experiment(n,t);
}
public static void experiment(int n,int t){
double[] wealth = new double[n];
Arrays.fill(wealth,100);
boolean[] hasMoney = new boolean[n];
for (int i = 0;i<t;i++){
Arrays.fill(hasMoney,false);
for(int j=0;j<n;j++){
if(wealth[j]>0){
hasMoney[j]=true;
}
}
for (int j=0;j<n;j++){
if(hasMoney[j]){
int other = j;
do{
other = (int)(Math.random()*n);
}while(other ==j);
wealth[j]--;
wealth[other]++;
}
}
}
Arrays.sort(wealth);
System.out.println("列出每个人的财富从贫穷到富有：");
for(int i =0;i<n;i++){
System.out.print((int)wealth[i]+ "");
if(i%10 ==9){
System.out.println();
}
}
System.out.println();
System.out.println("基尼系数为："+calculateGini(wealth));
}
public static double calculateGini(double[] wealth){
double sumOfAbsoluteDifferences = 0;
double sumOfWealth = 0;
int n = wealth.length;
for (int i=0;i<n;i++){
sumOfWealth += wealth[i];
for(int j =0;j<n;j++){
sumOfAbsoluteDifferences += Math.abs(wealth[i]-wealth[j]);
}
}
return sumOfAbsoluteDifferences/(2*n*sumOfWealth);
}