package com.yyq;
/*** Created by gao on 15-10-23.*/
public class MoreThanHalfNumber {public static boolean g_bInputInvalid = false;public static boolean checkInvalidArray(int[] numbers, int length) {g_bInputInvalid = false;if (numbers == null || length <= 0) {System.out.printf("Numbers is null! Invalid Parameters.");g_bInputInvalid = true;}return g_bInputInvalid;}public static boolean checkMoreThanHalf(int[] numbers, int length, int number) {int times = 0;for (int i = 0; i < length; i++) {if (number == numbers[i])times++;}boolean isMoreThanHalf = true;if (times * 2 <= length) {System.out.println("the number you find is not more than half.");isMoreThanHalf = false;g_bInputInvalid = true;}return isMoreThanHalf;}public static int Partition(int[] numbers, int length, int start, int end) {if (numbers == null || length <= 0 || start < 0 || end >= length) {System.out.printf("Invalid Parameters!");return -1;}int index = numbers[start];while (start < end) {while (start < end && numbers[end] >= index) end--;numbers[start] = numbers[end];while (start < end && numbers[start] <= index) start++;numbers[end] = numbers[start];}numbers[start] = index;return start;}//==================方法一:partition========================public static int moreThanHalfNum_solution1(int[] numbers, int length) {if (checkInvalidArray(numbers, length)) {return 0;}int middle = length >> 1;int start = 0;int end = length - 1;int index = Partition(numbers, length, start, end);while (index != middle) {if (index > middle) {end = index - 1;index = Partition(numbers, length, start, end);} else {start = index + 1;index = Partition(numbers, length, start, end);}}int result = numbers[middle];if (!checkMoreThanHalf(numbers, length, result)) {result = 0;}return result;}public static int moreThanHalfNum_solution2(int[] numbers, int length) {if (checkInvalidArray(numbers, length)) {return 0;}int result = numbers[0];int times = 1;for(int i = 1; i < length; i++){if (times == 0){result = numbers[i];times = 1;}else if(numbers[i] == result){times ++;}else{times--;}}if (!checkMoreThanHalf(numbers, length, result)) {result = 0;}return result;}
// ====================测试代码====================public static void Test(String testName, int[] numbers, int length, int expectedValue, boolean expectedFlag){if(testName != null)System.out.println("\n"+testName+" begins: ");int[] copy = new int[length];for(int i = 0; i < length; ++i)copy[i] = numbers[i];System.out.printf("Test for solution1: ");int result = moreThanHalfNum_solution1(numbers, length);if(result == expectedValue && g_bInputInvalid == expectedFlag)System.out.println("Passed.");elseSystem.out.println("Failed.");System.out.printf("Test for solution2: ");result = moreThanHalfNum_solution2(copy, length);if(result == expectedValue && g_bInputInvalid == expectedFlag)System.out.println("Passed.");elseSystem.out.println("Failed.");copy = null;}// 存在出现次数超过数组长度一半的数字public static void Test1(){int numbers[] = {1, 2, 3, 2, 2, 2, 5, 4, 2};Test("Test1", numbers, numbers.length, 2, false);}// 不存在出现次数超过数组长度一半的数字public static void Test2(){int numbers[] = {1, 2, 3, 2, 4, 2, 5, 2, 3};Test("Test2", numbers, numbers.length, 0, true);}// 出现次数超过数组长度一半的数字都出现在数组的前半部分public static void Test3(){int numbers[] = {2, 2, 2, 2, 2, 1, 3, 4, 5};Test("Test3", numbers, numbers.length, 2, false);}// 出现次数超过数组长度一半的数字都出现在数组的后半部分public static void Test4(){int numbers[] = {1, 3, 4, 5, 2, 2, 2, 2, 2};Test("Test4", numbers, numbers.length, 2, false);}// 数组为1个元素public static void Test5(){int numbers[] = {1};Test("Test5", numbers, 1, 1, false);}// 输入空指针public static void Test6(){Test("Test6", null, 0, 0, true);}public static void main(String[] args){Test1();Test2();Test3();Test4();Test5();Test6();}
}