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115 | #include "kanapka.h"
#include "message.h"
#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
int main(int argc, char *argv[]) {
int n = GetN();
int p = NumberOfNodes();
int k = MyNodeId();
int t;
long long res = 0, partialRes = 0, maxF = 0, maxB = 0, sumF = 0, sumB = 0, sumPrev = 0, maxPrev = 0, sumNext = 0, maxNext = 0, prefSum;
int block = (n / p) + (int)(n % p != 0);
if (k * block < n) {
// partial sums and maxes forward
int myBlockSize = min(n, (k + 1)*block) - k*block;
vector<int> tastes;
tastes.resize(myBlockSize);
vector<long long> prefS;
prefS.resize(myBlockSize);
for (int i = k*block; i < min(n, (k + 1)*block); i++) {
t = GetTaste(i);
tastes[i - k*block] = t;
prefS[i - k*block] = t + (i == k*block ? 0 : prefS[i - k*block - 1]);
}
sumF = prefS.back();
// get previous sum and max - forward
if (k > 0) {
Receive(k - 1);
sumPrev = GetLL(k - 1);
maxPrev = GetLL(k - 1);
}
maxF = max(maxF, maxPrev);
for (int i = 0; i < myBlockSize; i++) maxF = max(maxF, sumPrev + prefS[i]);
if ((k + 1)*block < n) {
PutLL(k + 1, sumF + sumPrev);
PutLL(k + 1, maxF);
Send(k + 1);
}
// back partial sums
for (int i = myBlockSize - 1; i >= 0; i--) {
int j = myBlockSize - 1 - i;
prefS[j] = tastes[i] + (j == 0 ? 0 : prefS[j - 1]);
}
sumB = prefS.back();
// get next sum and max - back
if ((k + 1)*block < n) {
Receive(k + 1);
sumNext = GetLL(k + 1);
maxNext = GetLL(k + 1);
}
maxB = max(maxB, maxNext);
for (int i = 0; i < myBlockSize; i++) maxB = max(maxB, sumNext + prefS[i]);
if (k > 0) {
PutLL(k - 1, sumB + sumNext);
PutLL(k - 1, maxB);
Send(k - 1);
}
// calculate partial results
// 'i' is a left end -> swap partial back sums
for (int i = 0; i < (myBlockSize - 1) / 2; i++)
swap(prefS[i], prefS[myBlockSize - 1 - i]);
for (int i = myBlockSize - 2; i >= 0; i--)
prefS[i] = max(prefS[i], prefS[i + 1]);
prefSum = sumPrev;
for (int i = 0; i < myBlockSize; i++) {
prefSum += tastes[i];
long long tail = sumNext + (i == myBlockSize - 1 ? 0 : prefS[i + 1]);
long long current = prefSum + max(maxNext, tail);
partialRes = max(partialRes, current);
}
// 'i' is a right end
for (int i = 0; i < myBlockSize; i++)
prefS[i] = tastes[i] + (i == 0 ? 0 : prefS[i - 1]);
for (int i = 1; i < myBlockSize; i++)
prefS[i] = max(prefS[i - 1], prefS[i]);
prefSum = sumNext;
for (int i = myBlockSize - 1; i >= 0; i--) {
prefSum += tastes[i];
long long tail = sumPrev + (i == 0 ? 0 : prefS[i - 1]);
long long current = prefSum + max(maxPrev, tail);
partialRes = max(partialRes, current);
}
}
// gather results
if (k == 0) {
res = max(res, partialRes);
for (int i = 1; i < p; i++) {
Receive(i);
partialRes = GetLL(i);
res = max(res, partialRes);
}
cout << res << endl;
}
else {
PutLL(0, partialRes);
Send(0);
}
return 0;
}
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