From ff16fed22f52415eb75b749f5d11211d6b6c5ab5 Mon Sep 17 00:00:00 2001
From: Ankit <50232341+imankit007@users.noreply.github.com>
Date: Wed, 27 Aug 2025 21:14:27 +0530
Subject: [PATCH] Update 3459.cpp

Changes:
Change DP state to 4D.
Remove variable hashNum in function dfs.

Description:
The value of grid[i][j] does not need to be included as a DP state variable because it does not change during iteration.
This reduction in dimensionality improves space complexity.
The existing solution exceeds the time limit on some test cases.
---
 .../3459.cpp                                  | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/solutions/3459. Length of Longest V-Shaped Diagonal Segment/3459.cpp b/solutions/3459. Length of Longest V-Shaped Diagonal Segment/3459.cpp
index 3a3e16bf4e0..9e001b624be 100644
--- a/solutions/3459. Length of Longest V-Shaped Diagonal Segment/3459.cpp	
+++ b/solutions/3459. Length of Longest V-Shaped Diagonal Segment/3459.cpp	
@@ -3,10 +3,10 @@ class Solution {
   int lenOfVDiagonal(vector<vector<int>>& grid) {
     const int m = grid.size();
     const int n = grid[0].size();
-    vector<vector<vector<vector<vector<int>>>>> mem(
-        m, vector<vector<vector<vector<int>>>>(
-               n, vector<vector<vector<int>>>(
-                      2, vector<vector<int>>(2, vector<int>(4, -1)))));
+    vector<vector<vector<vector<int>>>> mem(
+        m, vector<vector<vector<int>>>(
+               n, vector<vector<int>>(
+                      2, vector<int>(4, -1))));
     int res = 0;
 
     for (int i = 0; i < m; ++i)
@@ -25,15 +25,14 @@ class Solution {
   static constexpr int kDirs[4][2] = {{-1, 1}, {1, 1}, {1, -1}, {-1, -1}};
 
   int dfs(const vector<vector<int>>& grid, int i, int j, bool turned, int num,
-          int dir, vector<vector<vector<vector<vector<int>>>>>& mem) {
+          int dir, vector<vector<vector<vector<int>>>>& mem) {
     if (i < 0 || i == grid.size() || j < 0 || j == grid[0].size())
       return 0;
     if (grid[i][j] != num)
       return 0;
 
-    const int hashNum = max(0, num - 1);
-    if (mem[i][j][turned][hashNum][dir] != -1)
-      return mem[i][j][turned][hashNum][dir];
+    if (mem[i][j][turned][dir] != -1)
+      return mem[i][j][turned][dir];
 
     const int nextNum = num == 2 ? 0 : 2;
     const auto& [dx, dy] = kDirs[dir];
@@ -42,10 +41,10 @@ class Solution {
     if (!turned) {
       const int nextDir = (dir + 1) % 4;
       const auto& [nextDx, nextDy] = kDirs[nextDir];
-      res = max(res, 1 + dfs(grid, i + nextDx, j + nextDy, /*turned=*/true,
+      res = max(res, 1 + dfs(grid, i + nextDx, j + nextDy,/*turned=*/true,
                              nextNum, nextDir, mem));
     }
 
-    return mem[i][j][turned][hashNum][dir] = res;
+    return mem[i][j][turned][dir] = res;
   }
 };