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package class029;
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public class Code03_MaxLeftMaxRight {
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// 笨办法，但是好想
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public static int solution1(int[] arr) {
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if (arr == null || arr.length < 2) {
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return 0;
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}
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int N = arr.length;
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int ans = Integer.MIN_VALUE;
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for (int leftEnd = 0; leftEnd < N - 1; leftEnd++) {
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int leftMax = arr[0];
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for (int i = 1; i <= leftEnd; i++) {
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leftMax = Math.max(leftMax, arr[i]);
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}
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int rightMax = arr[leftEnd + 1];
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for (int i = leftEnd + 2; i < N; i++) {
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rightMax = Math.max(rightMax, arr[i]);
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}
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ans = Math.max(ans, Math.abs(leftMax - rightMax));
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}
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return ans;
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}
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// 好办法，是我们真正想测试的
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public static int solution2(int[] arr) {
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if (arr == null || arr.length < 2) {
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return 0;
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}
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int N = arr.length;
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int max = arr[0];
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for (int i = 1; i < N; i++) {
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max = Math.max(max, arr[i]);
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}
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return max - Math.min(arr[0], arr[N - 1]);
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}
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public static int[] randomArray(int maxLen, int maxValue) {
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int len = (int) (Math.random() * (maxLen + 1));
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int[] arr = new int[len];
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for (int i = 0; i < arr.length; i++) {
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arr[i] = (int) (Math.random() * (maxValue + 1)) - (int) (Math.random() * (maxValue + 1));
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}
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return arr;
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}
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public static void main(String[] args) {
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// 随机数组的最大长度
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int maxLen = 6;
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// 随机数组值的范围
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int maxValue = 30;
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// 测试次数
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int testTime = 3000000;
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System.out.println("如果没有错误信息打印，说明所有测试通过");
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System.out.println("测试开始");
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for (int i = 0; i < testTime; i++) {
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// 随机得到一个数组，长度也随机，每个值也随机
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int[] arr = randomArray(maxLen, maxValue);
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// 用方法1跑出答案1
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int ans1 = solution1(arr);
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// 用方法2跑出答案2
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int ans2 = solution2(arr);
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// 如果答案1和答案2不一样，提示出错了
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if (ans1 != ans2) {
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System.out.println("出错了！");
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System.out.println(ans1 + " , " + ans2);
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for (int k = 0; k < arr.length; k++) {
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System.out.print(arr[k] + " ");
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}
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System.out.println();
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break;
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}
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}
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System.out.println("测试结束");
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}
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}
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