题解 | 二维斐波那契数列

#include <stdio.h>
//注意栈溢出（取模条件解决）
int mod = 1000000007; 

long fbn_iter(long i, long j) {
    long dp[i + 1][j + 1];

    for (long x = 1; x <= i; x++) {
        dp[x][1] = 1;
    }

    for (long y = 1; y <= j; y++) {
        dp[1][y] = 1;
    }

    for (long x = 2; x <= i; x++) {
        for (long y = 2; y <= j; y++) {
            dp[x][y] = (dp[x - 1][y] + dp[x][y - 1]) % mod;
        }
    }

    return dp[i][j];
}

int main() {
    long i,j,a;
    scanf("%ld %ld", &i, &j);
    
    a = fbn_iter(i,j);
    printf("%ld\n", a);
    
    return 0;
}