# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
355440 | spatarel | Cat in a tree (BOI17_catinatree) | C++17 | 262 ms | 283400 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <stdio.h>
#include <algorithm>
#include <deque>
#include <vector>
const int MAX_N = 200000;
int N, D;
std::vector<int> children[MAX_N];
std::deque<int> maxN[MAX_N];
int depth[MAX_N];
void dfs(int u) {
depth[u] = 1;
int deepestChild = -1;
int secondDepth = 0;
for (int v : children[u]) {
dfs(v);
if (depth[u] <= 1 + depth[v]) {
secondDepth = depth[u];
depth[u] = 1 + depth[v];
deepestChild = v;
} else if (secondDepth < 1 + depth[v]) {
secondDepth = 1 + depth[v];
}
}
if (secondDepth >= D / 2) {
maxN[u] = std::deque<int>(1 + D);
maxN[u][0] = 1;
for (int v : children[u]) {
if (depth[v] > D - 1) {
maxN[u][0] += maxN[v][D - 1];
}
}
std::vector<int> maxAdd(1 + D);
for (int v : children[u]) {
for (int d = 0; d < D && d < depth[v]; d++) {
maxN[u][d + 1] += maxN[v][d];
}
for (int d = 0; d < D - d - 2 && d < depth[v]; d++) {
maxAdd[d + 1] = std::max(maxAdd[d + 1],
maxN[v][d] - (D - d - 2 < depth[v] ? maxN[v][D - d - 2] : 0));
}
}
for (int d = 0; d < D - d - 2; d++) {
maxN[u][d + 1] = maxAdd[d + 1] + maxN[u][D - d - 1];
}
for (int d = D - 1; d >= 1; d--) {
maxN[u][d - 1] = std::max(maxN[u][d - 1], maxN[u][d]);
}
} else {
//printf("u = %d\n", u);
//fflush(stdout);
std::vector<int> maxAdd(secondDepth + 1);
//printf("second depth = %d\n", secondDepth);
//fflush(stdout);
for (int v : children[u]) {
for (int d = 0; d < D - d - 2 && d < depth[v] && d + 1 <= secondDepth; d++) {
maxAdd[d + 1] = std::max(maxAdd[d + 1],
maxN[v][d] /* - maxN[v][D - d - 2] */);
}
}
//printf("tata\n");
//fflush(stdout);
if (deepestChild != -1) {
std::swap(maxN[u], maxN[deepestChild]);
}
//printf("mama\n");
//fflush(stdout);
maxN[u].push_front(0);
maxN[u][0] = 1;
for (int v : children[u]) {
if (depth[v] > D - 1) {
maxN[u][0] += maxN[v][D - 1];
}
}
//printf("maxN[u][0] = %d\n", maxN[u][0]);
//fflush(stdout);
for (int v : children[u]) {
if (v != deepestChild) {
for (int d = 0; d < D && d < depth[v]; d++) {
maxN[u][d + 1] += maxN[v][d];
}
}
}
for (int d = 0; d + 1 <= secondDepth; d++) {
maxN[u][d + 1] = maxAdd[d + 1] /* + maxN[u][D - d - 1] */;
}
for (int d = secondDepth + 1; d >= 1; d--) {
maxN[u][d - 1] = std::max(maxN[u][d - 1], maxN[u][d]);
}
}
/*
printf("maxN[%d] = {", u);
for (int d = 0; d < D && d < depth[u]; d++) {
printf("%d, ", maxN[u][d]);
}
printf("}\n");
fflush(stdout);//*/
}
int main() {
scanf("%d%d", &N, &D);
for (int i = 1; i < N; i++) {
int xi;
scanf("%d", &xi);
children[xi].push_back(i);
}
dfs(0);
int answer = maxN[0][0];
printf("%d\n", answer);
return 0;
}
Compilation message (stderr)
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