题目:数组中重复的数字
要求:在一个长度为n的数组里的所有数字都在0到n-1的范围内。 数组中某些数字是重复的,但不知道有几个数字是重复的。也不知道每个数字重复几次。请找出数组中任意一个重复的数字。 例如,如果输入长度为7的数组{2,3,1,0,2,5,3},那么对应的输出是第一个重复的数字2
1 class Solution { 2 public: 3 // Parameters: 4 // numbers: an array of integers 5 // length: the length of array numbers 6 // duplication: (Output) the duplicated number in the array number 7 // Return value: true if the input is valid, and there are some duplications in the array number 8 // otherwise false 9 bool duplicate(int numbers[], int length, int* duplication) { 10 11 } 12 };
解题代码:
1 class Solution { 2 public: 3 // Parameters: 4 // numbers: an array of integers 5 // length: the length of array numbers 6 // duplication: (Output) the duplicated number in the array number 7 // Return value: true if the input is valid, and there are some duplications in the array number 8 // otherwise false 9 bool duplicate(int numbers[], int length, int* duplication) { 10 if(numbers == nullptr || length <= 0) 11 return false; 12 for(int i=0; i<length; i++){ 13 if(numbers[i] < 0 || numbers[i] > length-1) 14 return false; 15 } 16 17 int i = 0; 18 while(i < length){ 19 if(numbers[i] == i) 20 i++; 21 else{ 22 int idx = numbers[i]; 23 if(numbers[i] == numbers[idx]){ 24 *duplication = numbers[i]; 25 return true; 26 } 27 else{ 28 int temp = numbers[i]; 29 numbers[i] = numbers[idx]; 30 numbers[idx] = temp; 31 i = 0; 32 } 33 34 } 35 } 36 return false; 37 } 38 };