一二题打卡过,第三题01子串想暴力混分,没想到ac了。第四题感觉方法没问题,一直卡在16%,g。第三题暴力:#include <iostream>#include <string>#include <vector>using namespace std;int number(string&amp; str, int left, int right) {int ans1 = 0, ans2 = 0;for (int i = left; i <= right; i++) {if ((i + str[i] - '0') % 2 == 0) {ans1++;} else {ans2++;}}return min(ans1, ans2);}int main() {string str;cin >> str;int n = str.size();int ans = 0;for (int i = 0; i < n; i++) {for (int j = i + 1; j < n; j++) {ans += number(str, i, j);}}cout << ans << endl;return 0;}