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package class010;
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public class Code03_EvenTimesOddTimes {
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// arr中，只有一种数，出现奇数次
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public static void printOddTimesNum1(int[] arr) {
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int eor = 0;
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for (int i = 0; i < arr.length; i++) {
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eor ^= arr[i];
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}
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System.out.println(eor);
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}
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// arr中，有两种数，出现奇数次
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public static void printOddTimesNum2(int[] arr) {
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int eor = 0;
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for (int i = 0; i < arr.length; i++) {
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eor ^= arr[i];
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}
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// eor = a ^ b
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// eor != 0
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// eor必然有一个位置上是1
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// 0110010000
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// 0000010000
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int rightOne = eor & (~eor + 1); // 提取出最右的1
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int onlyOne = 0; // e'
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for (int i = 0 ; i < arr.length;i++) {
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// arr[1] = 111100011110000
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// rightOne= 000000000010000
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if ((arr[i] & rightOne) != 0) {
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onlyOne ^= arr[i];
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}
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}
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System.out.println(onlyOne + " " + (eor ^ onlyOne));
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}
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public static int bit1counts(int N) {
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int count = 0;
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while(N != 0) {
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int rightOne = N & ((~N) + 1);
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count++;
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N -= rightOne;
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}
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return count;
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}
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public static int add(int a, int b) {
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int t = 0;
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while( b != 0) {
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t = a;
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a = a ^ b;
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b = ((t & b) << 1);
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}
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return a;
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}
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public static int minus(int a, int b) {
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// -b ~b + 1
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return add(a, add(~b , 1));
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}
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public static void main(String[] args) {
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int a = 5;
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int b = 7;
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System.out.println(minus(a,b));
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a = a ^ b;
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b = a ^ b;
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a = a ^ b;
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System.out.println(a);
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System.out.println(b);
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int[] arr1 = { 3, 3, 2, 3, 1, 1, 1, 3, 1, 1, 1 };
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printOddTimesNum1(arr1);
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int[] arr2 = { 4, 3, 4, 2, 2, 2, 4, 1, 1, 1, 3, 3, 1, 1, 1, 4, 2, 2 };
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printOddTimesNum2(arr2);
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}
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}
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