Submission #127217

#	Time	Username	Problem	Language	Result	Execution time	Memory
127217		roseanne_pcy	Match (CEOI16_match)	C++14	100 / 100	17 ms	12892 KiB

match

#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
using namespace std;
#define X first
#define Y second
#define pb push_back
typedef pair<int, int> ii;
typedef long long ll;

const int maxn = 1e5+5;

char S[maxn];
int n;

int dp[maxn][30];

char ans[maxn];

bool valid()
{
	stack<char> s;
	for(int i = 0; i< n; i++)
	{
		if(s.empty() || s.top() != S[i])
		{
			s.push(S[i]);
		}
		else s.pop();
	}
	return s.empty();
}

void solve(int L, int R)
{
	if(L> R) return;
	int opt = dp[R][S[L]-'a'];
	// printf("[%d %d] match %d\n", L, R, opt);
	assert(opt> L);
	ans[L] = '('; ans[opt] = ')';
	solve(L+1, opt-1); solve(opt+1, R);
}

int main()
{
	scanf("%s", S);
	n = strlen(S);
	if(!valid())
	{
		printf("-1\n"); return 0;
	}
	for(int j = 0; j< 26; j++)
	{
		if(S[0] == 'a'+j) dp[0][j] = 0;
		else dp[0][j] = -1;
	}
	for(int i = 1; i< n; i++)
	{
		int x = dp[i-1][S[i]-'a'];
		// printf("x = %d\n", x);
		for(int j = 0; j< 26; j++)
		{
			if(S[i] == 'a'+j) dp[i][j] = i;
			else if(x >= 1) dp[i][j] = dp[x-1][j];
			else dp[i][j] = -1;
			// printf("dp[%d][%d] = %d\n", i, j, dp[i][j]);
		}
	}
	solve(0, n-1);
	ans[n] = '\0';
	printf("%s\n", ans);
}

Compilation message (stderr)

match.cpp: In function 'int main()':
match.cpp:46:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s", S);
  ~~~~~^~~~~~~~~

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