类哈希计数

1.Counting Roads - AtCoder abc061_b - Virtual Judge (vjudge.net)

利用数组的值去替换数组的下标来简化计数过程

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 int n,m,a[51],b[51],c[51] = {0};
 5 
 6 int main(){
 7     cin >> n >> m;
 8     for (int i = 1; i <= m; i ++ )
 9     {
10     cin >> a[i] >> b[i];
11     c[a[i]] += 1; c[b[i]]+= 1;
12     }
13     
14     for (int i = 1; i <= n; i ++ )
15     cout << c[i] << endl;
16     return 0;
17 }