LeetCode_Ones and Zeroes

474. Ones and Zeroes

Medium

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

문제 풀이

코드

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

        for(int i=1; i<=len; i++){
            String s = strs[i-1];
            int[] cnt = count(s);
            int zeroCnt = cnt[0];
            int oneCnt = cnt[1];

            // 0-1 냅색
            for(int j=0; j<=m; j++){
                for(int k=0; k<=n; k++){
                    dp[i][j][k] = dp[i-1][j][k]; // 0-case - default

                    if(j >= zeroCnt && k >= oneCnt) dp[i][j][k] = Math.max(dp[i][j][k], dp[i-1][j-zeroCnt][k-oneCnt] + 1); // 1-case
                }
            }
        }

        return dp[len][m][n];
    }

    private int[] count(String s){
        int[] cnt = new int[2];
        for(int i=0; i<s.length(); i++){
            if(s.charAt(i) == '0') cnt[0]++;
            else cnt[1]++;
        }
        return cnt;
    }
}