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package class23;
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import java.util.HashMap;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Map.Entry;
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public class Code04_FindKMajority {
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public static void printHalfMajor(int[] arr) {
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int cand = 0;
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int HP = 0;
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for (int i = 0; i < arr.length; i++) {
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if (HP == 0) {
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cand = arr[i];
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HP = 1;
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} else if (arr[i] == cand) {
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HP++;
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} else {
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HP--;
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}
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}
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if(HP == 0) {
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System.out.println("no such number.");
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return;
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}
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HP = 0;
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for (int i = 0; i < arr.length; i++) {
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if (arr[i] == cand) {
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HP++;
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}
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}
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if (HP > arr.length / 2) {
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System.out.println(cand);
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} else {
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System.out.println("no such number.");
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}
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}
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public static void printKMajor(int[] arr, int K) {
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if (K < 2) {
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System.out.println("the value of K is invalid.");
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return;
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}
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// 攒候选，cands，候选表，最多K-1条记录！ > N / K次的数字，最多有K-1个
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HashMap<Integer, Integer> cands = new HashMap<Integer, Integer>();
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for (int i = 0; i != arr.length; i++) {
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if (cands.containsKey(arr[i])) {
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cands.put(arr[i], cands.get(arr[i]) + 1);
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} else { // arr[i] 不是候选
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if (cands.size() == K - 1) { // 当前数肯定不要！，每一个候选付出1点血量，血量变成0的候选，要删掉！
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allCandsMinusOne(cands);
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} else {
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cands.put(arr[i], 1);
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}
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}
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}
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// 所有可能的候选，都在cands表中！遍历一遍arr，每个候选收集真实次数
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HashMap<Integer, Integer> reals = getReals(arr, cands);
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boolean hasPrint = false;
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for (Entry<Integer, Integer> set : cands.entrySet()) {
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Integer key = set.getKey();
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if (reals.get(key) > arr.length / K) {
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hasPrint = true;
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System.out.print(key + " ");
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}
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}
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System.out.println(hasPrint ? "" : "no such number.");
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}
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public static void allCandsMinusOne(HashMap<Integer, Integer> map) {
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List<Integer> removeList = new LinkedList<Integer>();
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for (Entry<Integer, Integer> set : map.entrySet()) {
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Integer key = set.getKey();
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Integer value = set.getValue();
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if (value == 1) {
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removeList.add(key);
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}
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map.put(key, value - 1);
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}
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for (Integer removeKey : removeList) {
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map.remove(removeKey);
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}
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}
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public static HashMap<Integer, Integer> getReals(int[] arr,
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HashMap<Integer, Integer> cands) {
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HashMap<Integer, Integer> reals = new HashMap<Integer, Integer>();
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for (int i = 0; i != arr.length; i++) {
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int curNum = arr[i];
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if (cands.containsKey(curNum)) {
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if (reals.containsKey(curNum)) {
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reals.put(curNum, reals.get(curNum) + 1);
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} else {
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reals.put(curNum, 1);
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}
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}
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}
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return reals;
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}
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public static void main(String[] args) {
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int[] arr = { 1, 2, 3, 1, 1, 2, 1 };
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printHalfMajor(arr);
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int K = 4;
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printKMajor(arr, K);
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}
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}
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