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  1. // ~~ icebear love attttt ~~
  2. #include <bits/stdc++.h>
  3. using namespace std;
  4.  
  5. typedef long long ll;
  6. typedef pair<int, int> ii;
  7. typedef pair<int, ii> iii;
  8.  
  9. template<class T>
  10.     bool minimize(T &a, const T &b) {
  11.         if (a > b) return a = b, true;
  12.         return false;
  13.     }
  14.  
  15. template<class T>
  16.     bool maximize(T &a, const T &b) {
  17.         if (a < b) return a = b, true;
  18.         return false;
  19.     }
  20.  
  21. #define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
  22. #define FORR(i,a,b) for(int i=(a); i>=(b); --i)
  23. #define REP(i, n) for(int i=0; i<(n); ++i)
  24. #define RED(i, n) for(int i=(n)-1; i>=0; --i)
  25. #define MASK(i) (1LL << (i))
  26. #define BIT(S, i) (((S) >> (i)) & 1)
  27. #define mp make_pair
  28. #define pb push_back
  29. #define fi first
  30. #define se second
  31. #define all(x) x.begin(), x.end()
  32. #define task "icebearat"
  33.  
  34. const int MOD = 1e9 + 7;
  35. const int inf = 1e9 + 27092008;
  36. const ll INF = 1e18 + 27092008;
  37. const int N = 2025 + 5;
  38. int n, m, a[N][N];
  39. ll dp[N][N][3];
  40.  
  41. void init(void) {
  42.     cin >> n >> m;
  43.     FOR(i, 1, n) FOR(j, 1, m) cin >> a[i][j];
  44. }
  45.  
  46. void process(void) {
  47.     memset(dp, -0x3f, sizeof dp);
  48.     dp[1][0][0] = 0;
  49.     FOR(i, 1, n) FOR(j, 1, m) {
  50.         FOR(t, 0, 2) maximize(dp[i][j][0], dp[i][j - 1][t] + a[i][j]);
  51.         FOR(t, 1, 2)
  52.             maximize(dp[i][j][t], dp[i - 1][j][t - 1] + a[i][j]);
  53.     }
  54.     ll ans = 0;
  55.     FOR(t, 0, 2) maximize(ans, dp[n][m][t]);
  56.     cout << ans;
  57. }
  58.  
  59. int main() {
  60.     ios_base::sync_with_stdio(0);
  61.     cin.tie(0); cout.tie(0);
  62.     if (fopen(task".inp", "r")) {
  63.         freopen(task".inp", "r", stdin);
  64.         freopen(task".out", "w", stdout);
  65.     }
  66.     int tc = 1;
  67. //    cin >> tc;
  68.     while(tc--) {
  69.         init();
  70.         process();
  71.     }
  72.     return 0;
  73. }
  74.  
  75.  
Success #stdin #stdout 0.02s 101584KB
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https://ideone.com/D6wsLC
language:
C++14 (gcc 8.3)
created:
3 days ago
visibility:
public

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