// 2264. Largest 3-Same-Digit Number in String #include "leetcode.h" /* * given a string 'num' representing a large integer, an integer is good if it * meets the following conditions: if it is a substring of 'num' with length * '3', it consists of only one unique digit. return the maximum good integer as * a string or an empty string "" if no such integer. */ char *largestGoodInterger(char *num) { int n = strlen(num), chr = 'a', cnt = 1; for (int i = 1; i < n; i++) { if (num[i] == num[i - 1]) { cnt++; if (i < n - 1) continue; } if (cnt >= 3) { if (chr == 'a') chr = num[i - 1]; else chr = fmax(chr, num[i - 1]); } cnt = 1; } if (chr == 'a') return ""; else { char *ans = malloc(4); ans[3] = '\0'; ans[0] = chr; ans[1] = chr; ans[2] = chr; return ans; } } int main() { char *n1 = "6777133339", *n2 = "2300019", *n3 = "42352338"; printf("%s\n", largestGoodInterger(n1)); // expect: 777 printf("%s\n", largestGoodInterger(n2)); // expect: 000 printf("%s\n", largestGoodInterger(n3)); // expect: NULL }