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+// 440. K-th Smallest in Lexicographical Order
+#include "leetcode.h"
+// given two integers 'n' and 'k', return the k'th lexicographically smallest
+// integer
+
+class Soltuion {
+public:
+ int findKthNumber(int n, int k) {
+ int curr = 1;
+ for (--k; k > 0;) {
+ int cnt = 0;
+ for (long long first = static_cast<long long>(curr), last = first + 1;
+ first <= n; first *= 10, last *= 10)
+ cnt += static_cast<int>((min(n + 1LL, last) - first));
+ if (k >= cnt) {
+ ++curr;
+ k -= cnt;
+ } else {
+ curr *= 10;
+ --k;
+ }
+ }
+ return curr;
+ }
+};
+
+int main() {
+ Soltuion obj;
+ printf("%d\n", obj.findKthNumber(13, 2)); // expect: 10
+ printf("%d\n", obj.findKthNumber(1, 1)); // expect: 1
+}