Submission #341556

#	Time	Username	Problem	Language	Result	Execution time	Memory
341556		limabeans	Growing Vegetable is Fun 3 (JOI19_ho_t3)	C++17	0 / 100	70 ms	9324 KiB

joi2019_ho_t3

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

template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl





using ll = long long;


const int maxn = 444;
const int inf = 1e9;


int n;
string s;
int a[maxn];


map<vector<int>,int> dp[maxn][6];

int solve(int i, int last, vector<int> hold) {
    if (i==n) {
	int have = -1;
	for (int j=0; j<3; j++) {
	    if (hold[j] > 1) return inf;
	    if (hold[j] == 1) {
		if (~have) return inf;
		have = j;
	    }
	}
	if (have == last) return inf;
	return 0;
    } else {
	int sum = accumulate(hold.begin(), hold.end(), 0);
	if (dp[i][last].count(hold)) return dp[i][last][hold];
	int res = inf;
	
	// do nothing
	if (a[i] != last) {
	    res = min(res, sum+solve(i+1,a[i],hold));
	}
	// drop elem
	{
	    for (int j=0; j<3; j++) {
		if (hold[j]>0 && last!=j && a[i]!=j) {
		    auto nhold = hold;
		    nhold[j]--;
		    res = min(res, sum-1 + solve(i+1,a[i],nhold));
		}
	    }
	}
	
	// take elem
	{
	    auto nhold = hold;
	    nhold[a[i]]++;
	    res = min(res, sum+solve(i+1,last,nhold));
	}

	// drop elem and take elem
	{
	    for (int j=0; j<3; j++) {
		if (hold[j]>0 && last!=j) {
		    auto nhold = hold;
		    nhold[j]--;
		    nhold[a[i]]++;
		    res = min(res, sum + solve(i+1,j,nhold));
		}
	    }
	}
	return dp[i][last][hold] = res;	
    }
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);  cout.tie(0);

    cin>>n;
    cin>>s;
    for (int i=0; i<n; i++) {
	if (s[i]=='R') {
	    a[i]=0;
	} else if (s[i]=='G') {
	    a[i]=1;
	} else if (s[i]=='Y') {
	    a[i]=2;
	} else assert(false);
    }


    int res = solve(0,4,{0,0,0});
    
    if (res > inf/2) res = -1;
    cout<<res<<endl;    
    return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 55
• Subtask 3: 0 / 15
• Subtask 4: 0 / 25