算法导论：最大子数组问题（java实现）

import java.util.*;
public class Main{
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n;
n = in.nextInt();
int[] a = new int
;
int[] b = new int
;
for(int i=0;i<n;i++) {
a[i] = in.nextInt();
}
for(int i=1;i<n;i++) {
b[i] = a[i] - a[i-1];
}
b[0] = 0;
int[] result = subarray(b,1,n);
for(int e:result)
System.out.print(e+" ");
}
public static int[] crossSubarray(int[] a,int p,int q,int r) {
int left_sum = -100000;
int sum = 0;
int left_max=p;
for(int i=q-1;i>=p-1;i--) {
sum = sum+a[i];
if(sum>left_sum) {
left_sum = sum;
left_max = i;
}
}
int right_sum = -100000;
sum = 0;
int right_max=q;
for(int i=q;i<=r-1;i++) {
sum = sum+a[i];
if(sum>right_sum) {
right_sum = sum;
right_max = i;
}
}
int[] result = {left_max,right_max,left_sum+right_sum};
return result;
}
public static int[] subarray(int[] a,int p,int r) {
if(p==r) {
int[] x = {p,r,a[r-1]};
return x;
}
else {
int q = (p+r)/2;
int[] x1 = subarray(a,p,q);
int[] x2 = subarray(a,q+1,r);
int[] x3 = crossSubarray(a,p,q,r);
if(x1[2]>=x2[2]&&x1[2]>=x3[2])
return x1;
if(x2[2]>=x1[2]&&x2[2]>=x3[2])
return x2;
else
return x3;
}
}
}