Submission #483453

#	Time	Username	Problem	Language	Result	Execution time	Memory
483453		XII	Round words (IZhO13_rowords)	C++17	28 / 100	174 ms	63044 KiB

rowords

#include <bits/stdc++.h>
using namespace std;

using ll = long long;

#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
#define ALL(x) (x).begin(), (x).end()

#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define FORU(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)

#define IOS cin.tie(0)->sync_with_stdio(false);
#define PROB "rowords"
void Fi(){
    if(fopen(PROB".in", "r")){
        freopen(PROB".in", "r", stdin);
        freopen(PROB".out", "w", stdout);
    }
}

const int N = 2e3 + 1;
int dp[N * 2][N], t[N * 2][N];
int n, m, ans;
string s, p;

const int dx[] = {-1, 0, -1};
const int dy[] = {0, -1, -1};

void calc(){
    memset(dp, 0, sizeof(dp));
    memset(t, -1, sizeof(t));
    FORU(i, 1, n * 2) t[i][0] = 0;
    FORU(j, 1, m) t[0][j] = 1;
    FORU(i, 1, n * 2) FORU(j, 1, m){
        auto selection = {
            dp[i - 1][j],
            dp[i][j - 1],
            dp[i - 1][j - 1] + (s[i] == p[j])
        };
        dp[i][j] = *max_element(ALL(selection));
        t[i][j] = max_element(ALL(selection)) - selection.begin();
    }
    ans = max(ans, dp[n][m]);
    FORU(row, 1, n){
        {
            int i = row, j;
            for(j = 1; j <= m && t[i][j] != 2; ++j);
            if(j <= m){
                t[i][j] = 1;
                while(i < n * 2 && j <= m){
                    if(t[i + 1][j] == 0) t[++i][j] = 1;
                    else if(j == m) break;
                    else if(t[i + 1][j + 1] == 2) t[++i][++j] = 1;
                    else ++j;
                }
            }
        }
        {
            int tmp = 0;
            for(int i = n + row, j = m; i > row && j > 0;){
                int d = t[i][j];
                if(d == 2) ++tmp;
                i += dx[d], j += dy[d];
            }
            ans = max(ans, tmp);
        }
    }
}

int main(){
    IOS;
    Fi();
    cin >> s >> p;
    n = s.size(), m = p.size();
    s = " " + s + s;
    p = " " + p;
    calc();
    reverse(p.begin() + 1, p.begin() + m + 1);
    calc();
    cout << ans;
    return 0;
}

Compilation message (stderr)

rowords.cpp: In function 'void Fi()':
rowords.cpp:20:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |         freopen(PROB".in", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
rowords.cpp:21:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         freopen(PROB".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 28 / 100