[kiwi] srm_425_div1_250 dfs pruning

srm_425_div1_250.cpp

@@ -0,0 +1,37 @@
+#include <string.h>
+#include <iostream>
+
+using namespace std;
+
+int dx[] = {1,-1,0,0};
+int dy[] = {0,0,1,-1};
+
+class CrazyBot {
+public:
+	double P[4];
+	bool vis[50][50];
+	int N;
+
+	double solve(int x, int y, int n, double p) {
+		if (n == N) return p;
+
+		double res = 0;
+		for (int i = 0; i < 4; i++) {
+			if (!vis[x+dx[i]][y+dy[i]]) {
+				vis[x+dx[i]][y+dy[i]] = true;
+				res += solve(x+dx[i], y+dy[i], n+1, p*P[i]);
+				vis[x+dx[i]][y+dy[i]] = false;
+			}
+		}
+
+		return res;
+	}
+
+	double getProbability(int _N, int east, int west, int south, int north) {
+		P[0] = east/100.0; P[1] = west/100.0; P[2] = north/100.0; P[3] = south/100.0;
+		N = _N;
+		memset(vis, false, sizeof(vis));
+		vis[25][25] = true;
+		return solve(25, 25, 0, 1);
+	}
+};