Day 100 of 100 Days LeetCode Challenge

LeetCode Challenge #121. Best Time to Buy and Sell Stock

You are given an array prices where prices[i] is the price of a given stock on the ith day.

You want to maximize your profit by choosing a single day to buy one stock and choosing a different day in the future to sell that stock.

Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

 

Example 1:

Input: prices = [7,1,5,3,6,4]
Output: 5
Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.

Example 2:

Input: prices = [7,6,4,3,1]
Output: 0
Explanation: In this case, no transactions are done and the max profit = 0.

 

Constraints:

  • 1 <= prices.length <= 105
  • 0 <= prices[i] <= 104
Video Solution
Java Solution
				
					class Solution {
    public int maxProfit(int[] prices) {
        int n = prices.length;
        int[] maxValue = new int[n];
        maxValue[n-1] = prices[n-1];

        for(int i = n-2 ; i>=0;i--){
            maxValue[i] = Math.max(maxValue[i+1],prices[i]);
        }

        int ans = 0 ;
        for(int i=0;i<prices.length ;i++){
            int currPro = maxValue[i] - prices[i];
            ans = Math.max(ans , currPro);
        }
        return ans ;
    }
}
				
			

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