How to find dublicate in an Array-CodePudding

This method will check to see if number 'n'
- is in the array of integers stored in the method more than once
- It returns true if it is duplicated in the array and false
- if not
*/

My code :

for (int i = 0; i < myYears.length; i  ) {
        for (int j = 0; j < myYears.length; j  ) {
                      // got the duplicate element
                 System.out.println("Got dublicate");
                 return true;     
        }
    }
    return false;

However all i get is "got Dublicate" no matter the input.

Edit 1

package main;

public class Array1 {

public static void main(String[] args) {

    findMoreThanOneInArray(1231);      // test will return true

}  // end main

/*

 * This method will check to see if number 'n'

 * is in the array of integers stored in the method more than once

 * 

 * It returns true if it is duplicated in the array and false

 * if not

 */

private static boolean findMoreThanOneInArray(int n) {

    boolean result = false;     // default the search to false

    int[] myYears = { 2176, 2311, 2472, 2131, 2046, 2209, 2473, 2364, 2116, 2462, 2405, 2032, 2226, 2223, 2065, 2336, 2372, 2084, 2000, 2074, 2263, 2092, 2485, 2229, 2222, 2369, 2130, 2381, 2487, 2271, 2432, 2011, 2264, 2328, 2251, 2002, 2036, 2410, 2166, 2022, 2064, 2168, 2122, 2409, 2100, 2276, 2361, 2042, 2387, 2211, 2479, 2327, 2044, 2319, 2308, 2265, 2368, 2021, 2325, 2395, 2256, 2086, 2449, 2171, 2098, 2117, 2468, 2338, 2214, 2314, 2204, 2073, 2045, 2295, 2020, 2447, 2233, 2060, 2094, 2383, 2457, 2260, 2224, 2105, 2261, 2405, 2472, 2477, 2253, 2175, 2107, 2441, 2379, 2027, 2386, 2090, 2496, 2280, 2285, 2117 };


    /*

     * you code goes here

     * return true if n is duplicated in the array, false otherwise

     */
    for (int i = 0; i < myYears.length; i  ) {
        for (int j = i   1 ; j < myYears.length; j  ) {
            if (myYears[i] == myYears[j]) {
                 System.out.println("Got dublicate");
                 return true;
             }
        }
    }
    return false;
     

} // end of method

} // end class

Edit 2

for (int i = 0; i < myYears.length; i  ) {
        
            if (myYears[i] == n) {
                 System.out.println("Got dublicate");
                 return true;
             }
    }
   System.out.println("false");
    return false;

The Edit 2 passed all tests but one, for value of n = 2222; can anyone suggest why ?

Passed all tests but one

CodePudding user response：

I think this is what you are searching for...

int count = 0;
for (int i = 0; i < myYears.length; i  ) {    
    if (myYears[i] == n) {
        count  ;
    }
}
        
if (count >= 2) {
    System.out.println("true");
    return true; 
}

System.out.println("false");
return false;

This code basically increments the variable count every time by 1 if the given value is found in the array. After the for loop, we check if the variable count is greater or equal to the value 2 (because we need to know if the given number n is appearing more than once)

CodePudding user response：

I recommend floyd's tortoise and hare algorithm. Basically you treat array like graph and find cycle - which is your dublicate number

https://dev.to/alisabaj/floyd-s-tortoise-and-hare-algorithm-finding-a-cycle-in-a-linked-list-39af