Submission #508803

#	Time	Username	Problem	Language	Result	Execution time	Memory
508803		dutch	Round words (IZhO13_rowords)	C++17	80 / 100	1985 ms	46456 KiB

rowords

#include <bits/stdc++.h>
using namespace std;
 
const int Z = 2000, INF = 1e8;
 
string S, T;
int N, M, ans, d[Z*2][Z], p[Z*2][Z];
 
void dfs(int loR, int hiR, const int *lo, const int *hi) {
	if(loR > hiR) return;
 
	for(int j = 0; j < M; j++) {
		assert(lo[j] <= hi[j]);
		for(int i = lo[j]; i <= hi[j]; i++) 
			d[i][j] = INF;
	}
 
	int rt = (loR + hiR) / 2;
	deque<array<int, 2>> q;
	q.push_back({rt, d[rt][0] = 0});
 
	while(!empty(q)) {
		auto [i, j] = q.front();
		q.pop_front();
		for(int di : {0, 1}) for(int dj : {0, 1}) {
			int x = i + di, y = j + dj, w = di ^ dj;
			if(y == M || x > hi[y] || x < lo[y] || d[x][y] <= d[i][j] + w) continue;
			if(di && dj && S[i % N] != T[j]) continue;
 
			d[x][y] = d[i][j] + w;
			p[x][y] = di + 2 * dj;
			if(w) q.push_back({x, y});
			else q.push_front({x, y});
		}
	}
 
	int mMin[M], mMax[M] = {};
	fill(mMin, mMin+M, N+N);
 
	int i = rt+N-1, j = M-1;
 
	assert(lo[M-1] <= i && i <= hi[M-1]);
	ans = max(ans, N-1 + M-1 - d[i][j] + 2 * (S[i%N] == T[j]));
 
	while(1) {
		mMin[j] = min(mMin[j], i);
		mMax[j] = max(mMax[j], i);
		if(i == rt && !j) break;
		int k = p[i][j];
		if(k & 1) --i;
		if(k & 2) --j;
	}
 
	dfs(loR, rt - 1, lo, mMax);
	dfs(rt + 1, hiR, mMin, hi);
}
 
int main() {
	cin >> S >> T;
	N = size(S);
	M = size(T);
 
	for(int _ : {0, 1}) {
		if(_) reverse(begin(S), end(S));
		int lo[M] = {}, hi[M];
		fill(hi, hi + M, 2 * N - 1);
 
		dfs(0, N-1, lo, hi);
	}
	cout << ans / 2;
}

• Subtask 1: 80 / 100