贪心
不用去分类啥的，只考虑当前的最优解，即一天一天过
class Solution {
public int maxProfit(int[] prices) {
int n = prices.length;
int sum = 0;
for(int i =0;i<n-1;i++){
if(prices[i] < prices[i+1]){
sum += prices[i+1] - prices[i];
}
}
return sum;
}
}
状态转移
class Solution {
public int maxProfit(int[] prices) {
int n = prices.length;
int[][] dp = new int[n][2];
dp[0][0] = 0;
dp[0][1] = -prices[0];
for (int i = 1; i < n; ++i) {
dp[i][0] = Math.max(dp[i - 1][0], dp[i - 1][1] + prices[i]);
dp[i][1] = Math.max(dp[i - 1][1], dp[i - 1][0] - prices[i]);
}
return dp[n - 1][0];
}
}