USACO · 894

Grass Planting

This C++ solution uses tree degree counting for USACO 894 Grass Planting. Read the reasoning, inspect the code, or try your own test case below.

894Graphs & treesTree degree countingC++22 lines
Solution103of 248
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Approach

Tree degree counting

Count the degree of every field while reading the tree. The busiest field needs one different seed type for each incident path, plus one for itself, so the answer is maximum degree + 1.

TreesUSACO
Time
O(n)
Space
O(n)

Problem and code

Useful links.

Written by benbenyaojifen. Try the problem first, then compare your approach with the code.

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Implementation

grass_planting.cpp

C++

    #include <bits/stdc++.h>
    using namespace std;
    int main(){
        ios::sync_with_stdio(0);
        cin.tie(0);
        int n; cin >> n;
        vector<int> deg(n + 1, 0);
        for (int i = 0; i < n - 1; i++){
            int a, b; cin >> a >> b;
            deg[a]++;
            deg[b]++;
        }
        int mx = 0;
        for (int i = 1; i <= n; i++){
            if (deg[i] > mx){
                mx = deg[i];
            }
        }
        cout << mx + 1 << '\n';
        return 0;
    }
     
        

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