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| 1 | +// Problem Statement and Explanation: https://leetcode.com/problems/scramble-string/ |
| 2 | + |
| 3 | +/** |
| 4 | + * Given two strings s1 and s2 of the same length, return true if s2 is a scrambled string of s1, otherwise, return false. |
| 5 | + * @param {string} s1 |
| 6 | + * @param {string} s2 |
| 7 | + * @return {boolean} |
| 8 | + */ |
| 9 | + |
| 10 | +const isScramble = (s1, s2) => { |
| 11 | + return helper({}, s1, s2) |
| 12 | +} |
| 13 | + |
| 14 | +const helper = function (dp, s1, s2) { |
| 15 | + const map = {} |
| 16 | + |
| 17 | + if (dp[s1 + s2] !== undefined) return dp[s1 + s2] |
| 18 | + if (s1 === s2) return true |
| 19 | + |
| 20 | + for (let j = 0; j < s1.length; j++) { |
| 21 | + if (map[s1[j]] === undefined) map[s1[j]] = 0 |
| 22 | + if (map[s2[j]] === undefined) map[s2[j]] = 0 |
| 23 | + map[s1[j]]++ |
| 24 | + map[s2[j]]-- |
| 25 | + } |
| 26 | + |
| 27 | + for (const key in map) { |
| 28 | + if (map[key] !== 0) { |
| 29 | + dp[s1 + s2] = false |
| 30 | + return false |
| 31 | + } |
| 32 | + } |
| 33 | + |
| 34 | + for (let i = 1; i < s1.length; i++) { |
| 35 | + if ( |
| 36 | + (helper(dp, s1.substr(0, i), s2.substr(0, i)) && |
| 37 | + helper(dp, s1.substr(i), s2.substr(i))) || |
| 38 | + (helper(dp, s1.substr(0, i), s2.substr(s2.length - i)) && |
| 39 | + helper(dp, s1.substr(i), s2.substr(0, s2.length - i))) |
| 40 | + ) { |
| 41 | + dp[s1 + s2] = true |
| 42 | + return true |
| 43 | + } |
| 44 | + } |
| 45 | + |
| 46 | + dp[s1 + s2] = false |
| 47 | + return false |
| 48 | +} |
| 49 | + |
| 50 | +console.log(isScramble('great', 'rgeat')) |
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