55 lines
1.5 KiB
C++
55 lines
1.5 KiB
C++
#include <string>
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/**
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* 87. Scramble String
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* We can scramble a string s to get a string t using the following algorithm:
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*
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* If the length of the string is 1, stop.
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* If the length of the string is > 1, do the following:
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* Split the string into two non-empty substrings at a random index, i.e., if the string is s, divide it to x and y where s = x + y.
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* Randomly decide to swap the two substrings or to keep them in the same order. i.e., after this step, s may become s = x + y or s = y + x.
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* Apply step 1 recursively on each of the two substrings x and y.
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* Given two strings s1 and s2 of the same length, return true if s2 is a scrambled string of s1, otherwise, return false.
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*/
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class Solution {
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private:
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// Const Char Pointer
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using CCP = const char*;
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CCP s = nullptr, t = nullptr;
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int dp[31][31][31][31]{};
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bool f(int m, int n, int p, int q) {
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if (m + 1 == n)
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return s[m] == t[p];
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int& ans = dp[m][n][p][q];
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if (ans)
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return (ans + 1);
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ans = 1;
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for (int i = m, j = p; i < n; ++i, ++j) {
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if (s[i] != t[j]) {
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ans = 0;
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break;
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}
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}
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if (ans)
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return ans;
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for (int i = m + 1; i < n; ++i) {
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if (f(m, i, p, p - m + i) && f(i, n, p - m + i, q))
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return ans = 1;
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if (f(m, i, q - (i - m), q) && f(i, n, p, q - (i - m)))
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return ans = 1;
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}
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ans = -1;
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return false;
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}
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public:
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bool isScramble(const std::string& s1, const std::string& s2) {
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s = s1.c_str();
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t = s2.c_str();
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return f(0, s1.length(), 0, s2.length());
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}
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};
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