寻找数组的局部最小值

 

// 要求数组必须是相邻不相等的
public static int getLessIndex(int[] arr) {
	if (arr == null || arr.length == 0) {
		return -1;
	}
	if (arr.length == 1 || arr[0] < arr[1]) {
		return 0;
	}
	if (arr[arr.length - 1] < arr[arr.length - 2]) {
		return arr.length - 1;
	}
	int left = 1;
	int right = arr.length - 2;
	int mid = 0;
	while (left < right) {
		mid = (left + right) / 2;
		if (arr[mid] > arr[mid - 1]) {
			right = mid - 1;
		} else if (arr[mid] > arr[mid + 1]) {
			left = mid + 1;
		} else {
			return mid;
		}
	}
	return left;
}