java实现——8硬币问题（算法）

标签：8硬币问题   算法   java   

代码看着有点乱，有点复杂！单步调试一下其实不复杂！当然前提是要搞清楚算法的思想！

package yxd.sf.eightcoins;


public class EightCoins {

	public static int compareTo(int[] coins, int[] left, int[] right) {
		
		int leftTotal = 0;
		int rightTotal = 0;
		int fakeCoin = 0;
		int coinsSize = 0;
		
		if (coins.length % 2 == 0) {
			coinsSize = coins.length/2;			//将现在的硬币分成两半
			System.arraycopy(coins, 0, left, 0, coinsSize);		//前一半硬币放到left
			for (int i = 0; i < coinsSize; i++) {
				leftTotal = leftTotal + left[i]; 		//前一半硬币的总重量
			}
			System.arraycopy(coins, coinsSize, right, 0, coinsSize);		//后一半硬币放到right
			for (int j = 0; j < coinsSize; j++) {
				rightTotal = rightTotal + right[j];			//后一半硬币的总重量
			}
		}
		//比较right和left两边的硬币重量
		if (leftTotal < rightTotal && coinsSize != 1) {			
			coins = right;
			int[] right_1 = new int[coinsSize/2];
			int[] left_1 = new int[coinsSize/2];
			right = right_1;		//动态改变数组大小，减治后硬币减半
			left = left_1;
			System.arraycopy(coins, 0, left, 0, coinsSize/2);
			System.arraycopy(coins, coinsSize/2, right, 0, coinsSize/2);
		} else if (leftTotal > rightTotal && coinsSize != 1) {
			coins = left;
			int[] right_1 = new int[coinsSize/2];
			int[] left_1 = new int[coinsSize/2];
			right = right_1;
			left = left_1;
			System.arraycopy(coins, 0, left, 0, coinsSize/2);
			System.arraycopy(coins, coinsSize/2, right, 0, coinsSize/2);
		}
		if (left.length != 1 && right.length != 1 && fakeCoin == 0) {
			fakeCoin = compareTo(coins, left, right);    //递归调用，如果不令“fakeCoin=”最终返回会为0
		}
		if (left.length == 1 && right.length == 1 && coinsSize == 2) {
			if (left[0] < right[0]) {
				fakeCoin = right[0];
			} else if (left[0] == right[0]){
				System.out.println(left[0] + "and" + right[0]);
			} else {
				fakeCoin = left[0];
			}
		}
		return fakeCoin;
	}
	public static void main(String[] args) {
		int[] coins = {1, 1, 1, 2, 1, 1, 1, 1};
		int[] left = new int[4];
		int[] right = new int[4];
		int flag = 0;
		int location = compareTo(coins, left, right);
		for (int i = 0; i < coins.length; i++) {
			flag++;
			if (coins[i] == location) {
				System.out.println("第" + flag + "枚硬币为假币！");
			}
		}
	}

}

java实现——8硬币问题（算法）

标签：8硬币问题   算法   java   

原文地址：http://blog.csdn.net/yxdayd/article/details/46539095