Submission #221855

#	Time	Username	Problem	Language	Result	Execution time	Memory
221855		_7_7_	Lamps (JOI19_lamps)	C++14	0 / 100	1034 ms	31200 KiB

lamp

#include <bits/stdc++.h>                                           
 
//#define int long long
//#pragma GCC optimize("Ofast")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4")
 
 
#define file(s) freopen(s".in","r",stdin); freopen(s".out","w",stdout);
#define forev(i, b, a) for(int i = (b); i >= (a); --i)
#define forn(i, a, b) for(int i = (a); i <= (b); ++i)
#define all(x) x.begin(), x.end()
#define sz(s) (int)s.size()
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define s second
#define f first
 
 
using namespace std;
 
 
typedef pair < long long, long long > pll;    
typedef pair < int, int > pii;
typedef unsigned long long ull;         
typedef vector < pii > vpii;
typedef vector < int > vi;
typedef long double ldb;  
typedef long long ll;  
typedef double db;                             
 
 
const int inf = 1e9, maxn = 4e5 + 148, mod = 1e9 + 7, N = 1e6 + 11;
const int dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1}, block = 333;
const pii base = mp(1171, 3307), Mod = mp(1e9 + 7, 1e9 + 9);
const db eps = 1e-12, pi = 3.14159265359;
const ll INF = 1e18;


int n, dp[N][2], prv[N], T[N << 2][2];
char s[N], t[N];

void update (int pos, int lvl, int x, int v = 1, int tl = 0, int tr = n) {
	if (tl == tr) {
		T[v][lvl] = x;
		return;
	}

	int tm = (tl + tr) >> 1;
	if (pos <= tm)
		update(pos, lvl, x, v << 1, tl, tm);
	else	
		update(pos, lvl, x, v << 1 | 1, tm + 1, tr);
	T[v][lvl] = min(T[v << 1][lvl], T[v << 1 | 1][lvl]);
}

int get (int l, int r, int lvl, int v = 1, int tl = 0, int tr = n) {
	if (l > r || tl > r || l > tr)
		return inf;

	if (l <= tl && tr <= r)
		return T[v][lvl];

	int tm = (tl + tr) >> 1;
	return min(get(l, r, lvl, v << 1, tl, tm), get(l, r, lvl, v << 1 | 1, tm + 1, tr));
}

main () {
	scanf("%d\n%s\n%s", &n, s + 1, t + 1);
	for (int i = 1; i <= n; ++i) {
		prv[i] = i - 1;
		if (i > 1 && t[i] == t[i - 1])
			prv[i] = prv[i - 1];
	}	
		

	dp[0][1] = inf;
	update(0, 1, inf);

	int lst = 0;
	for (int i = 1; i <= n; ++i) {
		if (s[i] == t[i]) {
			dp[i][0] = min(dp[i - 1][0], min(get(prv[i], i - 1, 0) + 1, get(prv[i], i - 1, 1)));
			dp[i][1] = inf;
			lst = i;
		} else {
			dp[i][0] = min(get(prv[i], i - 1, 0), get(prv[i], i - 1, 1)) + 1;
			dp[i][1] = min(get(lst, i - 1, 0), get(lst, i - 1, 1)) + 1;
		} 

//		cerr << dp[i][0] << ' ' << dp[i][1] << endl;

		update(i, 0, dp[i][0]);
		update(i, 1, dp[i][1]);
	}


	cout << min(dp[n][0], dp[n][1]) << endl;		
}

Compilation message (stderr)

lamp.cpp:69:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main () {
       ^
lamp.cpp: In function 'int main()':
lamp.cpp:70:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d\n%s\n%s", &n, s + 1, t + 1);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 4
• Subtask 4: 0 / 49