AtCoder Regular Contest 103 E Tr/ee

Tr/ee

思路：按照下图所示连接

代码：

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize(4)
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pi acos(-1.0)
#define LL long long
//#define mp make_pair
#define pb push_back
#define ls rt<<1, l, m
#define rs rt<<1|1, m+1, r
#define ULL unsigned LL
#define pll pair<LL, LL>
#define pii pair<int, int>
#define piii pair<pii, pii>
#define mem(a, b) memset(a, b, sizeof(a))
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);
//head

const int N = 1e5 + 100;
char s[N];
bool vis[N];
int main() {
    scanf("%s", s);
    int n = strlen(s);
    for (int i = 0; i < n; i++) {
        if(s[i] == '1') vis[i+1] = true;
    }
    if(vis[1] == 0 || vis[n-1] == 0 || vis[n] == 1) {
        printf("-1
");
        return 0;
    }
    for (int i = 2; i < n-1; i++) {
        if(vis[i] != vis[n-i]) {
            printf("-1
");
            return 0;
        }
    }
    stack<int> st;
    for (int i = 1; i <= n; i++) {
        if(vis[i]) {
            while(!st.empty()) printf("%d %d
", st.top(), i), st.pop();
        }
        if(i != n)st.push(i);
    }
    while(!st.empty()) printf("%d %d
", st.top(), n), st.pop();
    return 0;
}