leetcode

2 Random Problems

3 files changed, 80 insertions(+), 0 deletions(-)

diff --git a/ Problems/0423.cpp b/ Problems/0423.cpp

@@ -0,0 +1,22 @@

class Solution {

public:

string originalDigits(const string &s) {

string word[10] = {"zero", "two", "six", "eight", "three", "seven", "five", "four", "one", "nine"};

uint8_t mapping[10] = {0, 2, 6, 8, 3, 7, 5, 4, 1, 9};

uint32_t count[26] = {0}, digits[10] = {0};

char *letters = "zwxghsvuoi";

string res;

for (const char c : s)

count[c - 'a']++;

for (int i = 0; i <= 9; i++) {

const int cnt = digits[mapping[i]] = count[letters[i] - 'a'];

for (const char c : word[i])

count[c - 'a'] -= cnt;

}

for (int i = 0; i <= 9; i++)

res += string(digits[i], '0' + i);

return res;

}

};

diff --git a/ Problems/0473.cpp b/ Problems/0473.cpp

@@ -0,0 +1,56 @@

// Backtracking: 4 ^ N

class Solution {

static bool find(const vector<int> &sticks, const int side, int idx, int crnt[4]) {

if (idx == size(sticks)) return crnt[0] == side && crnt[1] == side && crnt[2] == side;

for (int i = 0; i < 4; i++) {

if (crnt[i] + sticks[idx] > side) continue;

crnt[i] += sticks[idx];

if (find(sticks, side, idx + 1, crnt)) return true;

crnt[i] -= sticks[idx];

}

return false;

}

public:

bool makesquare(vector<int> &sticks) const {

const int sum = accumulate(begin(sticks), end(sticks), 0);

if (sum % 4 != 0) return false;

sort(begin(sticks), end(sticks), greater<>());

int crnt[4] = {sticks[0], 0};

return find(sticks, sum / 4, 1, crnt);

}

};

// DP: N * 2 ^ N

class Solution {

uint8_t dp[4][1 << 16] = {0};

bool find(const vector<int> &sticks, int left, int side, int crnt, uint16_t mask) {

if (dp[left][mask]) return false;

dp[left][mask] = 1;

if (crnt == side) left--, crnt = 0;

if (!left) return true;

for (int i = 0, msk = 1; i < size(sticks); i++, msk <<= 1) {

if (mask & msk) continue;

if (crnt + sticks[i] > side) continue;

if (find(sticks, left, side, crnt + sticks[i], mask | msk)) return true;

}

return false;

}

public:

bool makesquare(vector<int> &sticks) {

const int sum = accumulate(begin(sticks), end(sticks), 0);

if (sum % 4 != 0) return false;

const int side = sum / 4;

return find(sticks, 3, side, 0, 0);

}

};

diff --git a/ README.md b/ README.md

@@ -365,6 +365,7 @@ reference and a base for solving problems. | 0417 | Medium | [Pacific Atlantic Water Flow](Problems/0417.cpp) | | 0419 | Medium | [Battleships in a Board](Problems/0419.cpp) | | 0421 | Medium | [Maximum XOR of Two Numbers in an Array](Problems/0421.cpp) |

| 0423 | Medium | [Reconstruct Original Digits from English](Problems/0423.cpp) |

| 0424 | Medium | [Longest Repeating Character Replacement](Problems/0424.cpp) | | 0427 | Medium | [Construct Quad Tree](Problems/0427.cpp) | | 0429 | Medium | [N-ary Tree Level Order Traversal](Problems/0429.cpp) |

@@ -402,6 +403,7 @@ reference and a base for solving problems. | 0464 | Medium | [Can I Win](Problems/0464.cpp) | | 0467 | Medium | [Unique Substrings in Wraparound String](Problems/0467.cpp) | | 0472 | Hard | [Concatenated Words](Problems/0472.cpp) |

| 0473 | Medium | [Matchsticks to Square](Problems/0473.cpp) |

| 0476 | Easy | [Number Complement](Problems/0476.cpp) | | 0477 | Medium | [Total Hamming Distance](Problems/0477.cpp) | | 0481 | Medium | [Magical String](Problems/0481.cpp) |