CCF 201503-4 网络延时

#include "iostream"
#include "algorithm"

using namespace std;

int parent[10001];
int depth[10001][2]; // the maximum depth of two subtree + 1

int smallIdx(int x) {
  if(depth[x][0] < depth[x][1]) return 0;
  else return 1;
}

int bigIdx(int x) {
  if(depth[x][0] < depth[x][1]) return 1;
  else return 0;
}

int main() {
  int m, n, maxDepth = 0;
  cin >> m >> n;
  for(int i=2; i<=m; i++) {
    cin >> parent[i];
  }
  for(int i=m+1; i<=m+n; i++) {
    int p;
    cin >> p;
    depth[p][smallIdx(p)] = 1;
  }
  for(int i=m; i>=1; i--) {
    depth[parent[i]][smallIdx(parent[i])] = max(depth[i][bigIdx(i)] + 1, depth[parent[i]][smallIdx(parent[i])]);
    maxDepth = max(depth[i][0]+depth[i][1], maxDepth);
  }
  cout << maxDepth; 
}