leetcode

Daily Problem

2 files changed, 59 insertions(+), 0 deletions(-)

diff --git a/ Problems/0934.cpp b/ Problems/0934.cpp

@@ -0,0 +1,58 @@

class Solution {

static const constexpr int offs_x[] = {1, 0, -1, 0};

static const constexpr int offs_y[] = {0, 1, 0, -1};

int n;

bool valid(int i, int j) { return i >= 0 && i < n && j >= 0 && j < n; }

public:

int shortestBridge(vector<vector<int>> &grid) {

queue<pair<int, int>> dq1, dq2;

n = grid.size();

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

for (int j = 0; j < n; j++) {

if (!grid[i][j]) continue;

dq1.push({i, j});

grid[i][j] = 2;

goto parse;

}

}

return -1;

parse:

while (!dq1.empty()) {

auto [i, j] = dq1.front();

dq1.pop();

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

int a = i + offs_x[k], b = j + offs_y[k];

if (!valid(a, b)) continue;

if (grid[a][b] == 1)

dq1.push({a, b});

else if (grid[a][b] == 0)

dq2.push({a, b});

grid[a][b] = 2;

}

}

for (int lvl = 1; !dq2.empty(); lvl++) {

for (int k = dq2.size(); k > 0; k--) {

auto [i, j] = dq2.front();

dq2.pop();

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

int a = i + offs_x[k], b = j + offs_y[k];

if (!valid(a, b)) continue;

if (grid[a][b] == 1)

return lvl;

else if (grid[a][b] == 0)

dq2.push({a, b});

grid[a][b] = 2;

}

}

}

return -1;

}

};

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

@@ -367,6 +367,7 @@ for solving problems. | 0926 | Medium | [Flip String to Monotone Increasing](Problems/0926.cpp) | | 0931 | Medium | [Minimum Falling Path Sum](Problems/0931.cpp) | | 0933 | Easy | [Number of Recent Calls](Problems/0933.cpp) |

| 0934 | Medium | [Shortest Bridge](Problems/0934.cpp) |

| 0938 | Easy | [Range Sum of BST](Problems/0938.cpp) | | 0941 | Easy | [Valid Mountain Array](Problems/0941.cpp) | | 0944 | Easy | [Delete Columns to Make Sorted](Problems/0944.cpp) |