Submission #124705

#	Time	Username	Problem	Language	Result	Execution time	Memory
124705		eriksuenderhauf	Match (CEOI16_match)	C++11	100 / 100	22 ms	11384 KiB

match

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 5;
char str[MAXN];
int a[MAXN], nx[MAXN][26];

void solve(int l, int r) {
	if (l > r) return;
	if (str[l] == str[r]) {
		a[r] = 1;
		solve(l+1, r-1);
		return;
	}
	int mx = nx[r][str[l]-'a'];
	a[mx] = 1;
	solve(l+1,mx-1);
	solve(mx+1,r);
}

int main() {
	scanf("%s", str+1);
	int n = strlen(str+1);
	if (n & 1) return !printf("-1\n");
	stack<int> st;
	st.push(1);
	nx[1][str[1]-'a'] = 1;
	for (int i = 2; i <= n; i++) {
		if (!st.empty() && str[i] == str[st.top()])
			st.pop();
		else
			st.push(i);
		for (int j = 0; j < 26; j++)
			if (nx[i-1][str[i]-'a'])
				nx[i][j] = nx[nx[i-1][str[i]-'a']-1][j];
		nx[i][str[i]-'a'] = i;
	}
	if (!st.empty())
		return !printf("-1\n");
	solve(1, n);
	for (int i = 1; i <= n; i++)
		if (a[i])
			printf(")");
		else
			printf("(");
    return 0;
}

Compilation message (stderr)

match.cpp: In function 'int main()':
match.cpp:22:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s", str+1);
  ~~~~~^~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 27 / 27
• Subtask 3: 63 / 63