P1002 过河卒

Posted 2020-12-14 kyriech-francis

此题用滚动数组即可

#include <cstdio>
#include <cstring>
using namespace std;
typedef unsigned long long ull;
ull f[50][50];
int a[12] = {0, -1, -2, -2, -1, 1, 2, 2, 1, 0};
int b[12] = {0, 2, 1, -1, -2, -2, -1, 1, 2, 0};
int tx, ty;
int hx, hy;
bool d[50][50];
int main() {
    memset(d, false, sizeof d);
    scanf("%d%d%d%d", &tx, &ty, &hx, &hy);
    tx++, ty++, hx++, hy++;
    for (int i = 1; i <= 9; i++) {
        if (hx + a[i] > 0 && hy + b[i] > 0)
        d[hx + a[i]][hy + b[i]] = true;
    }
    f[1][1] = 1;
    for (int i = 1; i <= tx; i++) {
        for (int j = 1; j <= ty; j++) {
            if (i == 1 && j == 1)
                continue;
            if (d[i][j])
                continue;
            f[i][j] = f[i - 1][j] + f[i][j-1];
        }
    }
    printf("%lld", f[tx][ty]);
return 0;
}