【NOIP2008】【Luogu1149】火柴棒等式

problem

solution

codes

#include<iostream>
using namespace std;
int num(int x){
    int s[11] = {6,2,5,5,4,5,6,3,7,6};
    if(x == 0)return s[0];
    int ans = 0;
    while(x != 0){
        ans += s[x%10];
        x /= 10;
    }
    return ans;
}
int main(){
    int n, ans=0;
    cin>>n;
    for(int i = 0; i < 1000; i++)
        for(int j = 0; j < 1000; j++)
            if(num(i)+num(j)+num(i+j)+4 == n)
                ans++;
    cout<<ans;
    return 0;
}

#include<iostream>
using namespace std;
int num[11] = {6,2,5,5,4,5,6,3,7,6};
int main(){
    int n, ans = 0;  cin>>n;
    for(int i = 0; i < 1000; i++){
        for(int j = 0; j < 1000; j++){
            int a = i, b = j, c = i+j, t = 0;
            if(a == 0)t += num[0];
            if(b == 0)t += num[0];
            if(c == 0)t += num[0];
            while(a){
                t += num[a%10];
                a /= 10;
            }
            while(b){
                t += num[b%10];
                b /= 10;
            }
            while(c){
                t += num[c%10];
                c /= 10;
            }
            if(t == n-4) ans++;
        }
    }
    cout<<ans<<"\n";
    return 0;
}