Sdut 1125-New Game (DFS)

New game Time Limit: 1000 ms memory limit: 65536 k any questions? Click Here ^_^ Topic description new game is a new game that is played on an M * m Special board (number I is marked on line I of the Board. Given a number N, the player is required to move a piece from the upper left corner () to the lower right corner (M, M). When moving, the player can only move to the right or down. The number after moving is required to be n, and the number of turns is the least.

If the given n is correct, the contestant cannot find the mobile solution so that the number and the number of turns are N or the number of turns is not the least, and the contestant loses. Therefore, contestants must do everything they can to find a path that meets the conditions !! Enter two positive integers m, n (where M <= 16) to ensure data is resolved. The minimum number of turns in the output. Sample Input

4 22

Sample output

1

Search .. Basic pruning.

# Include <iostream> # include <cstdio> # include <algorithm> # include <queue> # include <cctype> # include <cstring> using namespace STD; int ma [18] [18], M, N, ans; bool vis [18] [18]; const int INF = 0x3f3f3f3f; int dir [2] [2] = {1, 0}, {0, 1}; void DFS (int x, int y, bool statu, int num, int sum) {// optimal shear if (Num> ans) return; // feasible shear if (sum> N) return; If (x = M & Y = m) {If (sum = N) ans = min (ANS, num); Return ;}for (INT I = 0; I <2; I ++) {int Tx = x + dir [I] [0]; int ty = Y + dir [I] [1]; if (TX> = 1 & TX <= M & ty> = 1 & ty <= M &&! Vis [TX] [ty]) {vis [TX] [ty] = 1; if (sum = 1) DFS (TX, Ty, I, num, sum + ma [TX] [ty]); else {if (I! = Statu) DFS (TX, Ty, I, num + 1, sum + ma [TX] [ty]); elsedfs (TX, Ty, I, num, sum + ma [TX] [ty]);} vis [TX] [ty] = 0 ;}} void Init () {for (INT I = 1; I <= m; I ++) for (Int J = 1; j <= m; j ++) Ma [I] [J] = I;} int main () {While (scanf ("% d", & M, & N )! = EOF) {memset (VIS, 0, sizeof (VIS); Init (); vis [1] [1] = 1; ans = inf; DFS, 1); printf ("% d \ n", ANS);} return 0 ;}

Sdut 1125-New Game (DFS)