如果将代码第三行改为：const int maxn = 1e6 + 5; 则程序有可能会出现数组越界。

#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e6 + 5;
int val[maxn];
char ch[maxn];
int p[maxn], cnt;
int ql[maxn], head1, tail1;
int q2[maxn], head2, tail2;
int get(){
if (head1 > tail1){

    return q2[head2++];

}

if (head2 > tail2){

    return ql[head1++];

}

return val[ql[head1]] < val[q2[head2]] ? ql[head1++] : q2[head2++];


}
void newnode(int a, int b){
val[++cnt] = val[a] + val[b];

p[a] = p[b] = cnt;

ch[a] = '0';

ch[b] = '1';

q2[++tail2] = cnt;


}
int main(){
int n;

scanf("%d", &n);

for (int i = 1; i <= n; i++){

    scanf("%d", &val[i]);

    ql[i] = i;

}

cnt = n;

head1 = l;

tail1 = n;

head2 = 1;

for (int i = 1; i < n; i++){

    int a = get(), b = get();

    newnode(a, b);

}

for (int i = 1; i <= n; i++){

    string ans;

    for (int j = i; j != cnt; j = p[j]){

        ans = ch[j] + ans;

    }

    cout << ans << '\n';

}

return 0;


}