日志17

1.第一次只出现一次的字符

#include<bits/stdc++.h>

using namespace std;

int main() {

string s;

cin >> s;

vector<int> count(26, 0);

for (char c : s) {

count[c - 'a']++;

}

for (char c : s) {

if (count[c - 'a'] == 1) {

cout << c << endl;

return 0;

}

}

cout << -1 << endl;

return 0;

}

2.回文拼接

#include<bits/stdc++.h>

using namespace std;

int main() {

int n;

string s;

cin >> n;

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

cin >> s;

int len = s.length();

bool flag = 0;

for(int j = 2; j <= len - 2; j++) { //枚举第一段字符长度

string s1 = s.substr(0, j);

string s2 = s.substr(j, len - j + 1);

string t1 = s1;

string t2 = s2;

reverse(t1.begin(), t1.end());//翻转

reverse(t2.begin(), t2.end());//翻转

if (s1 == t1 && s2 == t2) {//如果都是回文串

flag = 1;//标记为回文拼接

break;

}

}

if(flag == 1) {

cout << "Yes" << endl;

} else {

cout << "No" << endl;

}

}

return 0;

}