鍓戞寚 Offer 03. 鏁扮粍涓噸澶嶇殑鏁板瓧

Posted 2020-12-12

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package com.example.lettcode.offer;

import java.util.*;

/**
 * @Class FindRepeatNumber
 * @Description 鍓戞寚 Offer 03. 鏁扮粍涓噸澶嶇殑鏁板瓧
 * 鎵惧嚭鏁扮粍涓噸澶嶇殑鏁板瓧銆? * 鍦ㄤ竴涓暱搴︿负 n 鐨勬暟缁?nums 閲岀殑鎵€鏈夋暟瀛楅兘鍦?0锝瀗-1 鐨勮寖鍥村唴銆? * 鏁扮粍涓煇浜涙暟瀛楁槸閲嶅鐨勶紝浣嗕笉鐭ラ亾鏈夊嚑涓暟瀛楅噸澶嶄簡锛屼篃涓嶇煡閬撴瘡涓暟瀛楅噸澶嶄簡鍑犳銆傝鎵惧嚭鏁扮粍涓换鎰忎竴涓噸澶嶇殑鏁板瓧銆? * <p>
 * 绀轰緥 1锛? * 杈撳叆锛? * [2, 3, 1, 0, 2, 5, 3]
 * 杈撳嚭锛? 鎴?3
 * <p>
 * 闄愬埗锛? * 2 <= n <= 100000
 * @Author 
 * @Date 2020/6/26
 **/
public class FindRepeatNumber {
}

// 瑙ｆ硶1锛氬埄鐢↙ist锛屾椂闂村鏉傚害瓒呮椂
public static int findRepeatNumber(int[] nums) {
	List<Integer> integerList = new ArrayList<>();
	for (int i = 0; i < nums.length; i++) {
		if (integerList.contains(nums[i])) {break;}
		integerList.add(nums[i]);
	}
	return -1;
}

// 瑙ｆ硶2锛氬埄鐢⊿et
public static int findRepeatNumber(int[] nums) {
	Set<Integer> set = new HashSet<Integer>();
	int repeat = -1;
	for (int num : nums) {
		if (!set.add(num)) {
			repeat = num;
			break;
		}
	}
	return repeat;
}

// 瑙ｆ硶3锛氶鐩腑鎻愬埌闀垮害涓?n 鐨勬暟缁?nums 閲岀殑鎵€鏈夋暟瀛楅兘鍦?0锝瀗-1 鐨勮寖鍥村唴銆傛瀯寤轰竴涓瓑闀跨殑鏁扮粍锛屽彧瑕乶um[i]涓轰笅鏍囩殑鍏冪礌鐨勫€间笉涓?锛屽氨璇存槑鏇剧粡鍑虹幇杩?// 鏃堕棿澶嶆潅搴﹀拰绌洪棿澶嶆潅搴﹀潎涓篛(n)
public static int findRepeatNumber(int[] nums) {
	int[] temp = new int[nums.length];
	for (int i = 0; i < nums.length; i++) {
		if (temp[nums[i]] == 0) temp[nums[i]]++;
		else return nums[i];
	}
	return -1;
}

// 娴嬭瘯鐢ㄤ緥
public static void main(String[] args) {
	int[] nums = new int[]{2, 3, 1, 0, 2, 5, 3};
	int ans = findRepeatNumber(nums);
	System.out.println("demo01 result:" + ans);
        // leetcode涓婃湁涓祴璇曠敤渚嬮暱搴﹀湪10K宸﹀彸锛屽鏄撹秴鏃?}