3.23 美团前端&移动端笔试

第1题 回文串删除，**有差不多的原题

#include <iostream>
#include <string>
using namespace std;

int main() {
  cin.tie(0)->sync_with_stdio(false);
  int ans = 0;
  int n;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 0; i < n; i++) {
    int j = i;
    while (j < n && s[j] == s[i]) {
      j += 1;
    }
    ans += j - i - 1;
    i = j - 1;
  }
  cout << ans << endl;
}

第2题 置换环

#include <iostream>
#include <string>
#include <vector>
using namespace std;

int main() {
  cin.tie(0)->sync_with_stdio(false);
  int n;
  cin >> n;
  vector<int> a(n), p(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    a[i]--;
    p[a[i]] = i;
  }
  string s;
  cin >> s;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'W' && a[i] != i) {
      cout << -1 << "\n";
      return 0;
    }
  }
  int ans = 0;
  vector<int> vis(n);
  for (int i = 0; i < n; i++) {
    if (vis[i]) {
      continue;
    }
    int j = i;
    int circle = 0;
    while (!vis[j]) {
      circle += 1;
      vis[j] = 1;
      j = a[j];
    }
    ans += circle - 1;
  }
  cout << ans << "\n";
  return 0;
}