USACO-T017: Mother's Milk

/*
ID: mickyta1
TASK: milk3
LANG: C++
*/

#include <bits/stdc++.h>
using namespace std;

typedef tuple<int, int, int> tiii;

const int N = 20 + 5;

vector<int> ans;
int limA, limB, limC;
bool visit[6][N][N];

bool &visited(int a, int b, int c){
    if(a == 0){
        return visit[0][b][c];
    } else if(a == limA){
        return visit[1][b][c];
    } else if(b == 0){
        return visit[2][a][c];
    } else if(b == limB){
        return visit[3][a][c];
    } else if(c == 0){
        return visit[4][a][b];
    }
    return visit[5][a][b];
}

int main(){
    freopen("milk3.in", "r", stdin);
    freopen("milk3.out", "w", stdout);

    scanf("%d%d%d", &limA, &limB, &limC);
    queue<tiii> que;
    visited(0, 0, limC) = true;
    que.emplace(0, 0, limC);
    while(!que.empty()){
        int ua = get<0>(que.front());
        int ub = get<1>(que.front());
        int uc = get<2>(que.front());
        que.pop();
        if(ua == 0){
            ans.push_back(uc);
        }
        int va, vb, vc, mve;
        for(int i = 1; i <= 6; ++i){
            va = ua;
            vb = ub;
            vc = uc;
            if(i == 1){ // A -> B
                mve = min(ua, limB - ub);
                va -= mve;
                vb += mve;
            } else if(i == 2){ // B -> A
                mve = min(ub, limA - ua);
                vb -= mve;
                va += mve;
            } else if(i == 3){ // A -> C
                mve = min(ua, limC - uc);
                va -= mve;
                vc += mve;
            } else if(i == 4){ // C -> A
                mve = min(uc, limA - ua);
                vc -= mve;
                va += mve;
            } else if(i == 5){ // B -> C
                mve = min(ub, limC - uc);
                vb -= mve;
                vc += mve;
            } else { // C -> B
                mve = min(uc, limB - ub);
                vc -= mve;
                vb += mve;
            }
            if(!visited(va, vb, vc)){
                visited(va, vb, vc) = true;
                que.emplace(va, vb, vc);
            }
        }
    }
    sort(ans.begin(), ans.end());
    for(int i = 0; i < (int)ans.size() - 1; ++i){
        cout << ans[i] << ' ';
    }
    cout << ans.back() << '\n';

    fclose(stdin);
    fclose(stdout);
    return 0;
}