求大神指导 啊

import java.util.Scanner;
public class Main{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int n = input.nextInt();
int w = input.nextInt();
int[] gList = new int[n];
int[] pList = new int[n];
double[] gp = new double[n];
for(int i = 0; i < n; i++){
gList[i] = input.nextInt();
pList[i] = input.nextInt();
gp[i] = (double)pList[i] / gList[i];
}
double sum = 0;
for(int j = 0; j < n - 1; j++){
double maxGp = gp[j];
int maxG = gList[j], maxP = pList[j], index = j;
for(int i = j + 1; i < n; i++){
if(gp[i] > maxGp){
maxGp = gp[i];
maxG = gList[i];
maxP = pList[i];
index = i;
}
}
gp[index] = gp[j];
gp[j] = maxGp;
gList[index] = gList[j];
gList[j] = maxG;
pList[index] = pList[j];
pList[j] = maxP;
if(gList[j] > w){
sum += w * gp[j];
break;
}
else if(gList[j] == w){
sum += pList[j];
break;
}
else if(gList[j] < w){
w -= gList[j];
sum += pList[j];
}
}
System.out.println( (int)(sum * 10) / 10.0 );
}
}

做了两个小时，一直出错，不断调试，修改好几遍到了90分后就不会了，不知道错在哪里啊