From f3e8c575947be7453c8520077b7b38702a954ee0 Mon Sep 17 00:00:00 2001
From: developeSHG <developeSHG@gmail.com>
Date: Fri, 18 Aug 2023 23:49:10 +0900
Subject: [PATCH] TRIANGLE_PATH

---
 Algorithm/Algorithm/TRIANGLE_PATH.cpp | 85 +++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 Algorithm/Algorithm/TRIANGLE_PATH.cpp

diff --git a/Algorithm/Algorithm/TRIANGLE_PATH.cpp b/Algorithm/Algorithm/TRIANGLE_PATH.cpp
new file mode 100644
index 0000000..019ba4a
--- /dev/null
+++ b/Algorithm/Algorithm/TRIANGLE_PATH.cpp
@@ -0,0 +1,85 @@
+#include <iostream>
+#include <vector>
+#include <list>
+#include <stack>
+#include <queue>
+using namespace std;
+#include <thread>
+#include <windows.h>
+
+// 오늘의 주제 : 동적 계획법 (DP)
+// TRIANGLE_PATH
+// - (0,0)부터 시작해서 아래 or 아래우측으로 이동 가능
+// - 만나는 숫자를 모두 더함
+// - 더한 숫자가 최대가 되는 경로? 합?
+
+// 6
+// 1 2
+// 3 7 4
+// 9 4 1 7
+// 2 7 5 9 4
+
+int N;
+vector<vector<int>> board;
+vector<vector<int>> cache;
+vector<vector<int>> nextX;
+
+int path(int y, int x)
+{
+	// 기저 사항
+	//if (y == N - 1)
+	//	return board[y][x];
+	if (y == N)
+		return 0;
+
+	// 캐시 확인
+	int& ret = cache[y][x];
+	if (ret != -1)
+		return ret;
+
+	// 경로 기록
+	{
+		int nextBottom = path(y + 1, x);
+		int nextBottomRight = path(y + 1, x + 1);
+		if (nextBottom > nextBottomRight)
+			nextX[y][x] = x;
+		else
+			nextX[y][x] = x + 1;
+	}
+
+	// 적용
+	// board[y][x] + path(y + 1, x); // 아래로 갈 경우
+	// board[y][x] + path(y + 1, x + 1) // 대각선 어래로 갈경우
+	return ret = board[y][x] + max(path(y + 1, x), path(y + 1, x + 1));
+}
+
+int main()
+{
+	board = vector<vector<int>>
+	{
+		{6},
+		{1, 2},
+		{3, 7, 4},
+		{9, 4, 1, 7},
+		{2, 7, 5, 9, 4}
+	};
+
+	N = board.size();
+	cache = vector<vector<int>>(N, vector<int>(N, -1));
+	nextX = vector<vector<int>>(N, vector<int>(N));
+
+	int ret = path(0, 0);
+	cout << ret << endl;
+
+	// 경로 만들기
+	int y = 0;
+	int x = 0;
+
+	while (y < N)
+	{
+		cout << board[y][x] << " -> ";
+
+		x = nextX[y][x];
+		y++;
+	}
+}
\ No newline at end of file