LightOJ 1050 - Marbles（dp）

题目链接：LightOJ 1050 - Marbles

代码

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int maxn = 505;int R, B;double dp[maxn][maxn];void init () {    memset(dp, 0, sizeof(dp));    dp[0][1] = 1;    for (int i = 0; i <= 500; i++) {        for (int j = i + 1; j <= 500; j++) {            if (j > 1)                dp[i][j] = dp[i][j-2] * j / (i + j);            if (i)                dp[i][j] += dp[i-1][j-1] * i / (i + j);        }    }}int main () {    int cas;    scanf("%d", &cas);    init();    for (int kcas = 1; kcas <= cas; kcas++) {        scanf("%d%d", &R, &B);        printf("Case %d: %.6lf\n", kcas, dp[R][B]);    }    return 0;}