From 43af4da056f7fc668da9e8a7adea78a474585047 Mon Sep 17 00:00:00 2001
From: LittleSheep <littlesheep.code@hotmail.com>
Date: Sun, 14 Apr 2024 15:32:42 +0800
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---
 counting-people/main.cc | 46 +++++++++++++++++++++++++++++++++++++++++
 counting-people/main.in |  7 +++++++
 2 files changed, 53 insertions(+)
 create mode 100644 counting-people/main.cc
 create mode 100644 counting-people/main.in

diff --git a/counting-people/main.cc b/counting-people/main.cc
new file mode 100644
index 0000000..0cc60ad
--- /dev/null
+++ b/counting-people/main.cc
@@ -0,0 +1,46 @@
+#include <cstring>
+#include <iostream>
+#include <vector>
+using namespace std;
+
+const int MAXN = 1e5 + 5;
+
+vector<int> tree[MAXN];
+int amount[MAXN];
+int mem[MAXN][2];
+int N, Rt;
+
+int dfs(int node, int flag) {
+  if (mem[node][flag] > -1) {
+    return mem[node][flag];
+  }
+
+  mem[node][0] = 0;
+  mem[node][1] = amount[node];
+
+  for (int i = 0; i < tree[node].size(); i++) {
+    int leaf = tree[node][i];
+    mem[node][0] += max(dfs(leaf, 0), dfs(leaf, 1));
+    mem[node][1] += dfs(leaf, 0);
+  }
+
+  return mem[node][flag];
+}
+
+int main() {
+  // Init
+  cin >> N;
+  memset(mem, -1, sizeof mem);
+  for (int i = 0; i < N; i++) {
+    int depends, idx, c;
+    cin >> depends >> idx >> c;
+    amount[idx] = c;
+    if (depends == 0) {
+      Rt = idx;
+    } else {
+      tree[depends].push_back(idx);
+    }
+  }
+  // Calculating!
+  printf("%d", max(dfs(Rt, 1), dfs(Rt, 0)));
+}
diff --git a/counting-people/main.in b/counting-people/main.in
new file mode 100644
index 0000000..0c9f062
--- /dev/null
+++ b/counting-people/main.in
@@ -0,0 +1,7 @@
+6
+0 1 2
+1 2 4
+1 3 3
+2 4 3
+3 5 2
+3 6 4