力扣376 摆动序列https://leetcode-cn.com/problems/wiggle-subsequence/
题目描述：
如果连续数字之间的差严格地在正数和负数之间交替，则数字序列称为摆动序列。第一个差（如果存在的话）可能是正数或负数。少于两个元素的序列也是摆动序列。
例如， [1,7,4,9,2,5] 是一个摆动序列，因为差值 (6,-3,5,-7,3) 是正负交替出现的。相反, [1,4,7,2,5] 和 [1,7,4,5,5] 不是摆动序列，第一个序列是因为它的前两个差值都是正数，第二个序列是因为它的最后一个差值为零。
给定一个整数序列，返回作为摆动序列的最长子序列的长度。通过从原始序列中删除一些（也可以不删除）元素来获得子序列，剩下的元素保持其原始顺序。
示例 1:
输入: [1,7,4,9,2,5]
输出: 6
解释: 整个序列均为摆动序列。
我把preDiff = curDiff;放到if外面for里面（就是不是在更新Result时候才更新preDiff，而是随着i的增加，更新preDiff），就通不过了，这是为啥？想了一下没想通，也没想到怎么调试找原因。如果按照我所说的方式写代码，可以通过一部分测试用例，但是这个第26个用例通不过，目前还没有想通为什么。

#include<iostream>
#include<vector>
using namespace std;
class Solution {
    
    
public:
    int wiggleMaxLength(vector<int>& nums) {
    
    
        if (nums.size() <= 1) return nums.size();
        int curDiff = 0; // 当前一对差值
        int preDiff = 0; // 前一对差值
        int result = 1;  // 记录峰值个数，序列默认序列最右边有一个峰值
        for (int i = 1; i < nums.size(); i++) {
    
    
            curDiff = nums[i] - nums[i - 1];
            // 出现峰值
		      if ((curDiff > 0 && preDiff <= 0) || (preDiff >= 0 && curDiff < 0)) {
    
    
                result++;
                preDiff = curDiff;
            }
        }
        return result;
    }
};	
int main(){
    
    
	Solution s;
	int n[500]= {
    
    372,492,288,399,81,2,320,94,416,469,427,117,265,357,399,456,496,337,355,219,475,295,457,350,490,470,281,127,131,36,430,412,442,174,128,253,1,56,306,295,340,73,253,130,259,223,14,79,409,384,209,151,317,441,156,275,140,224,128,250,290,191,161,472,477,125,470,230,321,5,311,23,27,248,138,284,215,356,320,194,434,136,221,273,450,440,28,179,36,386,482,203,24,8,391,21,500,484,135,348,292,396,145,443,406,61,212,480,455,78,309,318,84,474,209,225,177,356,227,263,181,476,478,151,494,395,23,114,395,429,450,247,245,150,354,230,100,172,454,155,189,33,290,187,443,123,59,358,241,141,39,196,491,381,157,157,134,431,295,20,123,118,207,199,317,188,267,335,315,308,115,321,56,52,253,492,97,374,398,272,74,206,109,172,471,55,452,452,329,367,372,252,99,62,122,287,320,325,307,481,316,378,87,97,457,21,312,249,354,286,196,43,170,500,265,253,19,480,438,113,473,247,257,33,395,456,246,310,469,408,112,385,53,449,117,122,210,286,149,20,364,372,71,26,155,292,16,72,384,160,79,241,346,230,15,427,96,95,59,151,325,490,223,131,81,294,18,70,171,339,14,40,463,421,355,123,408,357,202,235,390,344,198,98,361,434,174,216,197,274,231,85,494,57,136,258,134,441,477,456,318,155,138,461,65,426,162,90,342,284,374,204,464,9,280,391,491,231,298,284,82,417,355,356,207,367,262,244,283,489,477,143,495,472,372,447,322,399,239,450,168,202,89,333,276,199,416,490,494,488,137,327,113,189,430,320,197,120,71,262,31,295,218,74,238,169,489,308,300,260,397,308,328,267,419,84,357,486,289,312,230,64,468,227,268,28,243,267,254,153,407,399,346,385,77,297,273,484,366,482,491,368,221,423,107,272,98,309,426,181,320,77,185,382,478,398,476,22,328,450,299,211,285,62,344,484,395,466,291,487,301,407,28,295,36,429,99,462,240,124,261,387,30,362,161,156,184,188,99,377,392,442,300,98,285,312,312,365,415,367,105,81,378,413,43,326,490,320,266,390,53,327,75,332,454,29,370,392,360,1,335,355,344,120,417,455,93,60,256,451,188,161,388,338,238,26,275,340,109,185};
	vector<int> nums(n,n+500);
	cout<<("%d",s.wiggleMaxLength(nums));
	return 0;
}

调试的话也没有想好怎么调= =。
做的主要工作就是把这个用例放到一个int n[500]的数组里面，然后赋值给vector<int>类型的数组，毕竟那个vector不能直接赋值= =。
原因的话也没想通= =。代码参考的别人的= =。