LeetCode problem : Best Time to Buy and Sell Stock

Problem

Say you have an array for which the i^th element is the price of a given stock on day i.

If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.

Code

int maxProfit(vector<int> &prices) {
    // IMPORTANT: Please reset any member data you declared, as
    // the same Solution instance will be reused for each test case.
    int n = prices.size();
    if(n < 2)
        return 0;
    for(int i = 0;i < n - 1;++i){
        prices[i] = (prices[i + 1] - prices[i]);
    }
    vector<int> M(n - 1);
    int max_sum = M[0] = prices[0];
    for(int i = 1;i < n - 1;++i){
        M[i] =  prices[i];
        if(M[i - 1] > 0)
            M[i] += M[i - 1];
        if(max_sum < M[i])
            max_sum = M[i];
    }
    return (max_sum > 0 ? max_sum : 0);
}