Formatted question description: https://leetcode.ca/all/879.html

879. Profitable Schemes

Level

Hard

Description

There are G people in a gang, and a list of various crimes they could commit.

The i-th crime generates a profit[i] and requires group[i] gang members to participate.

If a gang member participates in one crime, that member can’t participate in another crime.

Let’s call a profitable scheme any subset of these crimes that generates at least P profit, and the total number of gang members participating in that subset of crimes is at most G.

How many schemes can be chosen? Since the answer may be very large, return it modulo 10^9 + 7.

Example 1:

Input: G = 5, P = 3, group = [2,2], profit = [2,3]

Output: 2

Explanation:

To make a profit of at least 3, the gang could either commit crimes 0 and 1, or just crime 1.

In total, there are 2 schemes.

Example 2:

Input: G = 10, P = 5, group = [2,3,5], profit = [6,7,8]

Output: 7

Explanation:

To make a profit of at least 5, the gang could commit any crimes, as long as they commit one.

There are 7 possible schemes: (0), (1), (2), (0,1), (0,2), (1,2), and (0,1,2).

Note:

  1. 1 <= G <= 100
  2. 0 <= P <= 100
  3. 1 <= group[i] <= 100
  4. 0 <= profit[i] <= 100
  5. 1 <= group.length = profit.length <= 100

Solution

Use dynamic programming. Create a 3D array dp of size (group.length + 1) * (P + 1) * (G + 1), where dp[i][j][k] represents the number of profitable schemes for the i-th crime (1-indexed), there is already profit j and there are k gang members remaining. Initially, dp[0][0][G] = 1.

For index i, obtain curProfit = profit[i - 1] and curGroup = group[i - 1], and update the elements as dp[i][j + curProfit][k - curGroup] += dp[i - 1][j][k] and dp[i][j][k] += dp[i - 1][j][k]. Note that if j + curProfit > P, then use P instead of j + curProfit, and the first update is only applicable when k - curGroup >= 0.

Finally, calculate the sum of all the elements in dp[group.length][P] and return the sum.

class Solution {
    public int profitableSchemes(int G, int P, int[] group, int[] profit) {
        final int MODULO = 1000000007;
        int length = group.length;
        int[][][] dp = new int[length + 1][P + 1][G + 1];
        dp[0][0][G] = 1;
        for (int i = 1; i <= length; i++) {
            int curProfit = profit[i - 1];
            int curGroup = group[i - 1];
            for (int j = 0; j <= P; j++) {
                int totalProfit = Math.min(j + curProfit, P);
                for (int k = 0; k <= G; k++) {
                    if (k >= curGroup)
                        dp[i][totalProfit][k - curGroup] = (dp[i][totalProfit][k - curGroup] + dp[i - 1][j][k]) % MODULO;
                    dp[i][j][k] = (dp[i][j][k] + dp[i - 1][j][k]) % MODULO;
                }
            }
        }
        int schemes = 0;
        for (int i = 0; i <= G; i++)
            schemes = (schemes + dp[length][P][i]) % MODULO;
        return schemes;
    }
}

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