6월 1주차 Hojun

2023/06_June/week1/이호준/boj_17425_약수의합.cpp

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+/*******************************************************************
+Algorithm Study
+Baekjoon 17425 약수의 합
+2023/06/10 이호준
+# 아이디어
+1. 누적합
+*******************************************************************/
+#include <iostream>
+#define MAX 1000001
+
+using namespace std;
+typedef long long ll;
+
+ll dp[MAX];
+int main(void){
+
+    ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+
+    int t, n;
+    ll sum = 0;
+    cin >> t;
+
+    for(int i = 1; i <= MAX; ++i){
+        for(int j = i; j <= MAX; j+=i){
+            dp[j] += i;
+        }
+    }
+
+    for(int i = 2; i <= MAX; i++){
+        dp[i] += dp[i-1];
+    }
+
+    while (t--){
+        cin >> n;
+        cout << dp[n] <<"\n";
+    }
+
+    return 0;
+}

2023/06_June/week1/이호준/boj_177779_게더멘더링2.cpp

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+/*******************************************************************
+Algorithm Study
+Baekjoon 177779 게더멘더링2
+2023/06/11 이호준
+# 아이디어
+1. 구현
+*******************************************************************/
+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+int N, total;
+int answer = 2000000000;
+int A[25][25];
+
+// 구역 나누고, population 벡터에 각 구역 인구 저장
+void DivideArea(const int x, const int y, const int d1, const int d2, vector<vector<int>> &board, vector<int> &population)
+{
+    // 1
+    int cnt = 0;
+    for(int i = 1; i < x + d1; i++)
+    {
+        if(i >= x) cnt++;
+        for(int j = 1; j <= y - cnt; j++)
+        {
+            population[1] += A[i][j];
+        }
+    }
+
+    // 2
+    cnt = 0;
+    for(int i = 1; i <= x+d2; i++)
+    {
+        if(i > x) cnt++;
+        for(int j = y+1+cnt; j <= N; j++)
+        {
+            population[2] += A[i][j];
+        }
+    }
+
+    // 3
+    cnt = 0;
+    for(int i = N; i >= x + d1; i--)
+    {
+        if(i < x+d1+d2) cnt++;
+        for(int j = 1; j < y+d2-d1-cnt; j++)
+        {
+            population[3] += A[i][j];
+        }
+    }
+
+    // 4
+    cnt = 0;
+    for(int i = N; i > x+d2; i--)
+    {
+        if(i <= x+d1+d2) cnt++;
+        for(int j = y+d2-d1+cnt; j <= N; j++)
+        {
+            population[4] += A[i][j];
+        }
+    }
+}
+
+void Print(vector<vector<int>> board)
+{
+    cout << endl;
+    for(int i = 1; i <= N; i++)
+    {
+        for(int j = 1; j <= N; j++)
+        {
+            cout << board[i][j] << ' ';
+        } cout << endl;
+    } cout << endl;
+}
+
+
+int main()
+{
+    ios::sync_with_stdio(false); cin.tie(NULL);
+    cin >> N;
+    for(int i = 1; i <= N; i++)
+    {
+        for(int j = 1; j <= N; j++)
+        {
+            cin >> A[i][j];
+            total += A[i][j];
+        }
+    }
+
+    for(int x = 1; x < N; x++)
+    {
+        for(int y = 0; y < N; y++)
+        {
+
+            for(int d1 = 1; d1 < N; d1++)
+            {
+                for(int d2 = 1; d2 < N; d2++)
+                {
+                    if(x+d1 > N || y-d1 <= 0) continue; // 좌측 꼭지점
+                    if(x+d2 > N || y+d2 > N) continue; // 우측 꼭지점
+                    if(x+d1+d2 > N || y+d2-d1 <= 0) continue; // 아래 꼭지점
+                    if(x+d2+d1 > N || y-d1+d2 > N) continue;
+
+                    vector<vector<int>> board(N+1, vector<int>(N+1, 0));
+                    vector<int> population(6);
+                    DivideArea(x, y, d1, d2, board, population);
+                    population[5] = total - (population[1]+population[2]+population[3]+population[4]);
+                    sort(population.begin(), population.end());
+                    answer = min(answer, population[5] - population[1]);
+                }
+            }
+        }
+    }
+
+    cout << answer;
+}

2023/06_June/week1/이호준/boj_21278_호석이두마리치킨.cpp

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+/*******************************************************************
+Algorithm Study
+Baekjoon 21278 호석이 두 마리 치킨
+2023/06/10 이호준
+# 아이디어
+1. BruteForce, 플로이드와샬
+*******************************************************************/
+#include<iostream>
+#include<vector>
+#include<algorithm>
+
+#define INF 1000000000
+
+using namespace std;
+
+int n, m;
+int dist[101][101];
+
+int calDistance(int x, int y){
+	int distance = 0;
+	for (int i = 1; i <= n; i++)
+		distance += min(dist[x][i], dist[y][i]);
+	return distance;
+}
+
+void floydWarshall(){
+    for(int i = 1; i <= n; ++i){
+		for (int j = 1; j <= n; ++j) {
+			if (i == j) continue;
+			else if (!dist[i][j])
+				dist[i][j] = INF;
+		}
+    }
+	for (int k = 1; k <= n; ++k)
+		for (int i = 1; i <= n; ++i)
+			for (int j = 1; j <= n; ++j)
+				dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j]);
+}
+
+int main(void){
+	ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+
+	int x, y;
+	cin >> n >> m;
+	for (int i = 0; i < m; ++i) {
+		cin >> x >> y;
+		dist[x][y] = dist[y][x] = 1;
+	}
+
+    floydWarshall();
+
+    pair<int,int> chicken;
+    int answer = INF;
+	for (int i = 1; i <= n; i++)
+		for (int j = i + 1; j <= n; j++){
+			int temp = calDistance(i, j);
+			if (answer > temp) {
+				chicken = {i, j};
+				answer = temp;
+			}
+		}
+	cout << chicken.first <<" " << chicken.second <<" "<< answer * 2;
+	return 0;
+}

2023/06_June/week1/이호준/boj_21758_꿀따기.cpp

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+/*******************************************************************
+Algorithm Study
+Baekjoon 21758 꿀따기
+2023/06/11 이호준
+# 아이디어
+1. 누적합
+*******************************************************************/
+#include <iostream>
+
+#define MAX 100001
+
+using namespace std;
+
+int arr[MAX], sum[MAX];
+
+int getPrefixSum(int a, int b) {
+    return sum[b] - sum[a - 1]; 
+}
+
+int main(void){
+
+    ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+
+	int n;
+	cin >> n;
+
+	for (int i = 1; i <= n; i++){
+		cin >> arr[i];
+		sum[i] = sum[i - 1] + arr[i];
+	}
+
+	int res = 0;
+	for (int i = 2; i < n; i++)
+		res = max(res, getPrefixSum(2, n) + getPrefixSum(i + 1, n) - arr[i]);
+
+	for (int i = n - 1; i > 1; i--)
+		res = max(res, getPrefixSum(1, n - 1) + getPrefixSum(1, i - 1) - arr[i]);
+
+	for(int i = 2; i <= n - 1; i++)
+		res = max(res, getPrefixSum(2, n - 1) + arr[i]);
+
+	cout << res;
+	return 0;
+}

2023/06_June/week1/이호준/boj_22871_징검다리건너기(Large).cpp

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+/*******************************************************************
+Algorithm Study
+Baekjoon 22871 징검다리건너기(Large)
+2023/06/10 이호준
+# 아이디어
+1. DP
+*******************************************************************/
+#include <iostream>
+#include <algorithm>
+
+#define MAX 5001
+
+using namespace std;
+
+typedef long long ll;
+
+int N = 5001;
+int n;
+ll arr[MAX], dp[MAX];
+
+ll go(int x) {
+    if (x == n - 1) return 0;
+    ll& ret = dp[x];
+    if (ret != 0) return ret;
+
+    ret = 1e10;
+    for (int i = x + 1; i < n; i++) {
+        ret = min(ret, max(go(i), (i - x) * (1 + abs(arr[x] - arr[i]))));
+    }
+    return ret;
+}
+
+int main(void){
+    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+
+    cin >> n;
+
+    for (int i = 0; i < n; ++i)
+        cin >> arr[i];
+
+    cout << go(0);
+
+    return 0;
+}