题解 | 二维斐波那契数列

#include <stdio.h>
const int MOD=1e9+7;
int main() {
    int a, b;
    while (scanf("%d %d", &a, &b) != EOF) { // 注意 while 处理多个 case
        // 64 位输出请用 printf("%lld") to 
        int arr[1010][1010]={0};
        int i,j;
        arr[1][1] = 1;
        for (int i=2;i<=a;i++){
            arr[i][1] = 1;
        }
        for (int j =2;j<=b;j++){
            arr[1][j] = 1;
        }
        for(int i=2;i<=a;i++){
            for (int j=2;j<=b;j++){
                arr[i][j] = (arr[i-1][j] + arr[i][j-1]) % MOD; 
            }
        }
        printf("%d",arr[a][b]);
    }
    return 0;
}