474. Ones and Zeroes

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LeetCode

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Problem

You are given an array of binary strings strs and two integers m and n.

Return the size of the largest subset of strs such that there are at most m 0’s and n 1’s in the subset.

A set x is a subset of a set y if all elements of x are also elements of y.

Example 1:

Input: strs = ["10","0001","111001","1","0"], m = 5, n = 3
Output: 4
Explanation: The largest subset with at most 5 0's and 3 1's is {"10", "0001", "1", "0"}, so the answer is 4.
Other valid but smaller subsets include {"0001", "1"} and {"10", "1", "0"}.
{"111001"} is an invalid subset because it contains 4 1's, greater than the maximum of 3.

Example 2:

Input: strs = ["10","0","1"], m = 1, n = 1
Output: 2
Explanation: The largest subset is {"0", "1"}, so the answer is 2.

Constraints:

• 1 <= strs.length <= 600
• 1 <= strs[i].length <= 100
• strs[i] consists only of digits ‘0’ and ‘1’.
• 1 <= m, n <= 100

Code

416 - 有限数字组成和

class Solution {
    public int findMaxForm(String[] strs, int m, int n) {
        int[][] dp = new int[m + 1][n + 1];

        for(String str : strs){
            int zeroCount = 0;
            int oneCount = 0;
            
            for(char c : str.toCharArray()){
                if(c == '0'){
                    zeroCount++;
                } else {
                    oneCount++;
                }
            }

            for(int i = m; i >= zeroCount; i--){
                for(int j = n; j >= oneCount; j--){
                    dp[i][j] = Math.max(dp[i][j], dp[i - zeroCount][j - oneCount] + 1);
                }
            }
        }

        return dp[m][n];
    }
}