2024-03-05 석유 시추

Munbin-Lee/README.md

@@ -37,4 +37,5 @@
 | 34차시 | 2024.02.06 |  구현  | <a href="https://www.acmicpc.net/problem/1756">피자 굽기</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/133 |
 | 35차시 | 2024.02.18 |  백트래킹  | <a href="https://www.acmicpc.net/problem/24891">단어 마방진</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/140 |
 | 36차시 | 2024.02.21 |  문자열  | <a href="https://www.acmicpc.net/problem/15927">회문은 회문아니야!!</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/143 |
+| 37차시 | 2024.03.05 |  백트래킹  | <a href="https://school.programmers.co.kr/learn/courses/30/lessons/250136">석유 시추</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/150 |
 ---

Munbin-Lee/백트래킹/37-석유 시추.cpp

@@ -0,0 +1,78 @@
+#include <iostream>
+#include <vector>
+#include <queue>
+#include <unordered_set>
+
+using namespace std;
+
+int solution(vector<vector<int>> land) {
+    int r = land.size();
+    int c = land[0].size();
+
+    int dy[4] {-1, 0, 1, 0};
+    int dx[4] {0, -1, 0, 1};
+
+    vector<vector<int>> chunks(r, vector<int> (c, -1));
+    vector<int> oils;
+
+    auto bfs = [&](int y, int x, int chunk) {
+        queue<pair<int, int>> q;
+        q.emplace(y, x);
+
+        int oil = 0;
+
+        while (!q.empty()) {
+            auto [cy, cx] = q.front();
+            q.pop();
+
+            oil++;
+            chunks[cy][cx] = chunk;
+
+            for (int dir = 0; dir < 4; dir++) {
+                int ny = cy + dy[dir];
+                int nx = cx + dx[dir];
+
+                if (ny == -1 || ny == r || nx == -1 || nx == c) continue;
+                if (land[ny][nx] == 0) continue;
+
+                land[ny][nx] = 0;
+                q.emplace(ny, nx);
+            }
+        }
+
+        oils.emplace_back(oil);
+    };
+
+    for (int y = 0; y < r; y++) {
+        for (int x = 0; x < c; x++) {
+            if (land[y][x] == 0) continue;
+
+            land[y][x] = 0;
+            bfs(y, x, oils.size());
+        }
+    }
+
+    int answer = -1;
+
+    for (int x = 0; x < c; x++) {
+        unordered_set<int> set;
+
+        for (int y = 0; y < r; y++) {
+            int chunk = chunks[y][x];
+
+            if (chunk == -1) continue;
+
+            set.emplace(chunk);
+        }
+
+        int oil = 0;
+
+        for (int chunk : set) {
+            oil += oils[chunk];
+        }
+
+        answer = max(answer, oil);
+    }
+
+    return answer;
+}