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Commit bfd26d2

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Added tasks 204-206.
1 parent 1a70769 commit bfd26d2

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6 files changed

+128
-0
lines changed

6 files changed

+128
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lines changed
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package g0201_0300.s0204_count_primes;
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public class Solution {
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public int countPrimes(int n) {
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boolean[] isprime = new boolean[n];
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int count = 0;
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for (int i = 2; i * i <= n; i++) {
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if (!isprime[i]) {
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for (int j = i * 2; j < n; j += i) {
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isprime[j] = true;
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}
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}
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}
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for (int i = 2; i < isprime.length; i++) {
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if (!isprime[i]) {
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count++;
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}
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}
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return count;
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}
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}
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package g0201_0300.s0205_isomorphic_strings;
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public class Solution {
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public boolean isIsomorphic(String s, String t) {
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int[] map = new int[128];
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char[] str = s.toCharArray();
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char[] tar = t.toCharArray();
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int n = str.length;
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for (int i = 0; i < n; i++) {
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if (map[tar[i]] == 0) {
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if (search(map, str[i], tar[i]) != -1) {
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return false;
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}
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map[tar[i]] = str[i];
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} else {
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if (map[tar[i]] != str[i]) {
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return false;
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}
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}
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}
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return true;
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}
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private int search(int[] map, int tar, int skip) {
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for (int i = 0; i < 128; i++) {
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if (i == skip) {
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continue;
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}
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if (map[i] != 0 && map[i] == tar) {
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return i;
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}
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}
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return -1;
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}
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}
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package g0201_0300.s0206_reverse_linked_list;
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import com_github_leetcode.ListNode;
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public class Solution {
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public ListNode reverseList(ListNode head) {
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ListNode prev = null;
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ListNode curr = head;
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while (curr != null) {
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ListNode next = curr.next;
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curr.next = prev;
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prev = curr;
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curr = next;
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}
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return prev;
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}
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}
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package g0201_0300.s0204_count_primes;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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import org.junit.Test;
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public class SolutionTest {
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@Test
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public void countPrimes() {
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assertThat(new Solution().countPrimes(10), equalTo(4));
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}
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}
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package g0201_0300.s0205_isomorphic_strings;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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import org.junit.Test;
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public class SolutionTest {
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@Test
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public void isIsomorphic() {
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assertThat(new Solution().isIsomorphic("egg", "add"), equalTo(true));
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}
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@Test
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public void isIsomorphic2() {
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assertThat(new Solution().isIsomorphic("foo", "bar"), equalTo(false));
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}
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@Test
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public void isIsomorphic3() {
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assertThat(new Solution().isIsomorphic("paper", "title"), equalTo(true));
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}
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}
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package g0201_0300.s0206_reverse_linked_list;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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import com_github_leetcode.ListNode;
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import org.junit.Test;
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public class SolutionTest {
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@Test
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public void reverseList() {
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ListNode headActual = new ListNode(1);
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headActual.next = new ListNode(2);
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headActual.next.next = new ListNode(3);
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headActual.next.next.next = new ListNode(4);
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headActual.next.next.next.next = new ListNode(5);
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assertThat(new Solution().reverseList(headActual).toString(), equalTo("5, 4, 3, 2, 1"));
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}
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}

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