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package class01;
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import java.util.Arrays;
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public class Code05_BSNearLeft {
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// 在arr上，找满足>=value的最左位置
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public static int nearestIndex(int[] arr, int value) {
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int L = 0;
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int R = arr.length - 1;
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int index = -1; // 记录最左的对号
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while (L <= R) { // 至少一个数的时候
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int mid = L + ((R - L) >> 1);
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if (arr[mid] >= value) {
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index = mid;
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R = mid - 1;
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} else {
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L = mid + 1;
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}
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}
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return index;
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}
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// for test
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public static int test(int[] arr, int value) {
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for (int i = 0; i < arr.length; i++) {
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if (arr[i] >= value) {
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return i;
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}
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}
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return -1;
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}
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// for test
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public static int[] generateRandomArray(int maxSize, int maxValue) {
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int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
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for (int i = 0; i < arr.length; i++) {
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arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
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}
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return arr;
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}
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// for test
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public static void printArray(int[] arr) {
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if (arr == null) {
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return;
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}
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for (int i = 0; i < arr.length; i++) {
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System.out.print(arr[i] + " ");
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}
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System.out.println();
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}
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public static void main(String[] args) {
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int testTime = 500000;
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int maxSize = 10;
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int maxValue = 100;
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boolean succeed = true;
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for (int i = 0; i < testTime; i++) {
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int[] arr = generateRandomArray(maxSize, maxValue);
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Arrays.sort(arr);
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int value = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
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if (test(arr, value) != nearestIndex(arr, value)) {
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printArray(arr);
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System.out.println(value);
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System.out.println(test(arr, value));
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System.out.println(nearestIndex(arr, value));
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succeed = false;
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break;
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}
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}
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System.out.println(succeed ? "Nice!" : "Fucking fucked!");
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}
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}
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