Competitive-Coding/brick_coloring.cpp at main · S-Rohan-1904/Competitive-Coding · GitHub

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

#define rep(i, l, r) for (int i = l; i < r; i++)
#define rrep(i, r, l) for (int i = r-1; i >=0; i--)
#define ll long long
#define nline '\n'
#define prn cout << "NO" << nline
#define pry cout << "YES" << nline
#define vi vector<int>
#define vvi vector<vi>
#define eb emplace_back
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define inparr(v)   \
  for (auto &x : v) \
    cin >> x;
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vpii vector<pii>
#define vvpii vector<vector<pii>>
#define mp make_pair
#define ff first
#define ss second
#define float long double

#define int long long

//---- Debugger ---- //
#ifdef LOCAL
#define debarr(a,n) cout<<#a<<" : ";for(int i=0;i<n;i++) cerr<<a[i]<<" "; cerr<<nline;
#define debmat(mat,row,col) cout<<#mat<<" :\n";for(int i=0;i<row;i++) {for(int j=0;j<col;j++) cerr<<mat[i][j]<<" ";cerr<<nline;}
#define pr(...) dbs(#__VA_ARGS__, __VA_ARGS__)
template <class S, class T>ostream& operator <<(ostream& os, const pair<S, T>& p) {return os << "(" << p.first << ", " << p.second << ")";}
template <class T>ostream& operator <<(ostream& os, const vector<T>& p) {os << "[ "; for (auto& it : p) os << it << " "; return os << "]";}
template <class T>ostream& operator <<(ostream& os, const unordered_set<T>& p) {os << "[ "; for (auto& it : p) os << it << " "; return os << "]";}
template <class S, class T>ostream& operator <<(ostream& os, const unordered_map<S, T>& p) {os << "[ "; for (auto& it : p) os << it << " "; return os << "]";}
template <class T>ostream& operator <<(ostream& os, const set<T>& p) {os << "[ "; for (auto& it : p) os << it << " "; return os << "]";}
template <class T>ostream& operator <<(ostream& os, const multiset<T>& p) {os << "[ "; for (auto& it : p) os << it << " "; return os << "]";}
template <class S, class T>ostream& operator <<(ostream& os, const map<S, T>& p) {os << "[ "; for (auto& it : p) os << it << " "; return os << "]";}
template <class T> void dbs(string str, T t) {cerr << str << " : " << t << "\n";}
template <class T, class... S> void dbs(string str, T t, S... s) {int idx = str.find(','); cerr << str.substr(0, idx) << " : " << t << ","; dbs(str.substr(idx + 1), s...);}
template <class T> void prc(T a, T b) {cerr << "["; for (T i = a; i != b; ++i) {if (i != a) cerr << ", "; cerr << *i;} cerr << "]\n";}
#else
#define pr(...)
#endif
//----------------- //

const int MOD = 1e9 + 7;
const int INF = 1e9 + 1;

// Form 1
// dp(i, k) -> number of ways you can colour the brick wall such that there are exactly k different coloured neighbour from [i...n]
int n,m;

int dp[2001][2001];

int rec(int i, int k) {
    if(k < 0) return 0;
    if(i == n) {
        if(k==0) return 1;
        return 0;
    }
    if(dp[i][k] != -1) return dp[i][k];

    int ans = 0;
    if(i == 0) ans = (m * rec(i+1, k)) % MOD;
    else ans = (((m-1)*rec(i+1, k-1))%MOD + (rec(i+1, k)) % MOD) % MOD;

    dp[i][k] = ans;
    return ans;
}

void solve() {
    cin>>n>>m;
    int k;
    cin>>k;
    cout << (rec(0, k))%MOD << nline;
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    cin >> t;
    while (t--) {
        memset(dp, -1, sizeof(dp));
        solve();

    }
}