算法小记——二分查找

目录

二分查找

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二分查找

public class MyTest3 {
    public static void main(String[] args) {
        int[] arr = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100};
        int index = getIndex(arr, 30);
        System.out.println(index);
    }

    private static int getIndex(int[] arr, int i) {
        int minIndex = 0;
        int maxIndex = arr.length - 1;
        int centerIndex = (minIndex + maxIndex) / 2;
        while (minIndex <= maxIndex) {
            if (i == arr[centerIndex]) {
                return centerIndex;
            } else if (i < arr[centerIndex]) {
                maxIndex = centerIndex - 1;
            } else if (i > arr[centerIndex]) {
                minIndex = centerIndex + 1;
            }
            centerIndex = (minIndex + maxIndex) / 2;
        }
        return -1;
    }


}