Leetcode•Mar 14, 2026
Ones and Zeroes
Hazrat Ali
Leetcode
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.
Solution
var findMaxForm = function(strs, m, n) {
let dp = Array.from({ length: m + 1 }, () => Array(n + 1).fill(0));
for (let s of strs) {
let zeros = 0, ones = 0;
for (let ch of s) {
if (ch === '0') zeros++;
else ones++;
}
for (let i = m; i >= zeros; i--) {
for (let j = n; j >= ones; j--) {
dp[i][j] = Math.max(dp[i][j], dp[i - zeros][j - ones] + 1);
}
}
}
return dp[m][n];
};