1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
#include <iostream>
#include "maklib.h"
#include "message.h"
#include <algorithm>

using namespace std;

int getMaxCrossingSubarray(int begin, int end, int k){
	if(begin >= end) return 0;
	int a=0, b=0, s=0;
	for(int i=k; i>=begin; i--){
		s += ElementAt(i);
		if(s > a) a = s;
	}
	s=0;
	for(int i=k+1; i<end; i++){
		s += ElementAt(i);
		if(s > b) b = s;
	}
	return a+b;
}

int getMaxSubarray(int begin, int end){
	if(begin >= end) return 0;
	int k = (begin+end)/2;
	int a = getMaxSubarray(begin, k);
	int b = getMaxSubarray(k+1, end);
	int c = getMaxCrossingSubarray(begin, end, k);
	if(a>=b && a>=c) return a;
	if(b>=c) return b;
	return c;
}

int main(){
	int l = Size()/(NumberOfNodes()-1),ma,k,x;
	if(l==0) l=1;
	int a=min((MyNodeId()-1)*l, NumberOfNodes()-1);
	int b=min(MyNodeId()*l, NumberOfNodes()-1);
	int c=MyNodeId()/2;
	PutInt(c, a);
	PutInt(c, b);
	PutInt(c, getMaxSubarray(a,b));
	Send(c);
	while(true){
		x = MyNodeId()*2;
		if(x >= NumberOfNodes()) return 0;
		Receive(c);
		a = GetInt(x);
		b = GetInt(x);
		ma = GetInt(x++);
		k = (a+b)/2;
		if(x < NumberOfNodes()){
			Receive(x);
			k = GetInt(x);
			b = GetInt(x);
			ma = max(ma, GetInt(x));
		}
		x = max(ma, getMaxCrossingSubarray(a,b,k));
		if(!MyNodeId() && a==1 && b==NumberOfNodes()-1){
			cout<<x;
			return 0;
		}
		PutInt(c, a);
		PutInt(c, b);
		PutInt(c, x);
		Send(c);
	}
	return 0;
}