//-Si puedes imaginarlo, puedes programarlo- Alejandro Taboada #include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace std; using namespace __gnu_pbds; template<typename T> using ordered_set = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>; #define fst first #define snd second #define pb push_back #define sz(x) (int)x.size() #define rep(i,x,n) for(__typeof(n)i=(x);i!=(n);i+=1-2*((x)>(n))) #define dbg(x) cout << #x << "=" << x << " "; #define line cout << "\n.......................................................\n"; const int MOD = 1e9+7; int n, cs, cf, dp[10][1<<10][3]; int solve(int pos, int msk, int dir){ if(pos==cf) return __builtin_popcount(msk) == n-1; msk |= 1<<pos; int& ret=dp[pos][msk][dir]; if(ret!=-1) return ret; ret=0; if(dir == 2){ rep(i,0,n) if(!(msk & (1<<i))){ ret += solve(i, msk, i < pos); ret %= MOD; } } else if(dir == 1){ rep(i,pos+1,n) if(!(msk & (1<<i))){ ret += solve(i, msk, 0); ret %= MOD; } } else{ rep(i,pos-1,-1) if(!(msk & (1<<i))){ ret += solve(i, msk, 1); ret %= MOD; } } return ret; } int main(){ scanf("%d%d%d",&n,&cs,&cf); cs--, cf--; memset(dp,-1,sizeof(dp)); printf("%d\n", solve(cs,0,2)); return 0; }

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:51:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |  scanf("%d%d%d",&n,&cs,&cf);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~