Submission #54207922

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Source Code Expand

// LUOGU_RID: 161219767
#include<bits/stdc++.h>
using namespace std;
int len,A[200010],N;
char str[200010],now = 'a';
bool vis[200010][26];
void newnow(){
	now++;
	if(now > 'z') now = 'a';
}
int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin >> N;
	for(int i = 1;i <= N;++i){
		cin >> A[i];
		A[i] /= 2;
	}
	str[1] = 'a';len = 1;
	for(int i = 2;i <= N;++i){
		if(len < i){
			//newnow();
			while(vis[i][now-'a']) newnow();
			str[++len] = now;
		}
		for(int t = len-i+1;t <= A[i];++t){str[i+t] = str[i-t];}
		len = max(len,i+A[i]);
		if(i-A[i]-1 != 0) vis[i+A[i]+1][str[i-A[i]-1]-'a'] = 1;
	}
	cout << (str+1);
	return 0;
}

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