/** * 创建人：yang.liu * 创建时间：2019/7/17 17:53 * 版本：1.0 * 内容描述：求最大子序列问题 */ public class MaxSubSequenceSample { public static void main(String[] args) { var arr = new int[]{-1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -9, 20, -6, 5}; int i = maxSubSequence(arr); System.out.println(i); int i1 = maxSubSequence2(arr); System.out.println(i1); } /** * 时间复杂度为O(n^2) */ public static int maxSubSequence(int[] arr) { int maxSum = 0; for (int i = 0; i < arr.length; i++) { int iSum = 0; for (int j = i; j < arr.length; j++) { iSum += arr[j]; if (iSum > maxSum) { maxSum = iSum; } } } return maxSum; } /** * Kadane算法 * 时间复杂度为O(n^2) * 视频讲解：https://www.bilibili.com/video/av52421507?from=search&seid=3623534585276596200 * https://www.youtube.com/watch?v=86CQq3pKSUw */ public static int maxSubSequence2(int[] arr) { int maxSum = arr[0]; int iSum = 0; for (int i = 0; i < arr.length; i++) { iSum = Math.max(arr[i], iSum + arr[i]); if (iSum < 0) { iSum = 0; } if (iSum > maxSum) { maxSum = iSum; } } return maxSum; } } /** * 欢迎评论、留言、发表看法。谢谢！ */