leetcode

Daily problem + one hard

3 files changed, 64 insertions(+), 0 deletions(-)

diff --git a/ Problems/0134.cpp b/ Problems/0134.cpp

@@ -0,0 +1,15 @@

class Solution {

public:

int canCompleteCircuit(vector<int> &gas, vector<int> &cost) {

int start = 0, total = 0, tank = 0;

for (int i = 0; i < gas.size(); i++) {

tank = tank + gas[i] - cost[i];

if (tank < 0) {

start = i + 1;

total += tank;

tank = 0;

}

}

return (total + tank >= 0) ? start : -1;

}

};

diff --git a/ Problems/0135.cpp b/ Problems/0135.cpp

@@ -0,0 +1,47 @@

// original solution - accepted

class Solution {

public:

int candy(vector<int> &ratings) {

// place holder rating for easy neighbor calculation

ratings.insert(ratings.begin(), -1), ratings.push_back(-1);

int n = ratings.size();

// sort by rating remembering the original index

vector<pair<int, int>> vec;

vec.reserve(n);

for (int i = 1; i < n - 1; i++) vec.push_back({ratings[i], i});

sort(vec.begin(), vec.end());

vector<int> res(n, 1); // 'Each child must have at least one candy'

res.front() = res.back() = 0; // except placeholders

for (auto &[rating, index] : vec) {

if (rating < ratings[index + 1])

res[index + 1] = max(res[index + 1], res[index] + 1);

if (rating < ratings[index - 1])

res[index - 1] = max(res[index - 1], res[index] + 1);

}

return accumulate(res.begin(), res.end(), 0);

}

};

// improved solution - same logic no nonsense

class Solution {

public:

int candy(vector<int> &ratings) {

int n = ratings.size();

if (n <= 1) return n;

vector<int> res(n, 1);

for (int i = 0; i < n - 1; i++) {

if (ratings[i] < ratings[i + 1]) res[i + 1] = res[i] + 1;

}

for (int i = n - 1; i > 0; i--) {

if (ratings[i] < ratings[i - 1]) res[i - 1] = max(res[i - 1], res[i] + 1);

}

return accumulate(res.begin(), res.end(), 0);

}

};

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

@@ -76,6 +76,8 @@ for solving problems. | 0125 | Easy | [Valid Palindrome](Problems/0125.cpp) | | 0129 | Medium | [Sum Root to Leaf Numbers](Problems/0129.cpp) | | 0133 | Medium | [Clone Graph](Problems/0133.cpp) |

| 0134 | Medium | [Gas Station](Problems/0134.cpp) |

| 0135 | Hard | [Candy](Problems/0135.cpp) |

| 0138 | Medium | [Copy List with Random Pointer](Problems/0138.cpp) | | 0141 | Easy | [Linked List Cycle](Problems/0141.cpp) | | 0142 | Medium | [Linked List Cycle II](Problems/0142.cpp) |