pku3620 Avoid The Lakes

vector修改前后，iterator可能发生不可预知的变化，必须谨慎！

 

//pku3620 Avoid The Lakes#include <cstdio>#include <vector>using namespace std;typedef long INT32;const INT32 MAX_N = 100;enum STAT { ST_DRY=0, ST_SUBMERGE, ST_TRAVELED };typedef struct tagPOS{INT32 x;INT32 y;tagPOS(INT32 _x, INT32 _y) { x=_x; y=_y; }inline tagPOS operator+ (const tagPOS& in) const { return tagPOS(x+in.x, y+in.y); }} POS;vector<POS> vSubmergeCells, vQueue;STAT grid[MAX_N+2][MAX_N+2];POS aDirection[4] = {POS(0,1), POS(1,0), POS(0,-1), POS(-1,0)};int main(){INT32 iN, iM, iK;INT32 i;INT32 iMaxSize = 0;scanf("%ld %ld %ld", &iN, &iM, &iK);for (i=0; i<iK; i++){INT32 x, y;scanf("%ld %ld", &x, &y);vSubmergeCells.push_back(POS(x,y));grid[x][y] = ST_SUBMERGE;}vector<POS>::iterator iter;for (iter=vSubmergeCells.begin(); iter!=vSubmergeCells.end(); ++iter){const POS posStart = *iter;if (ST_SUBMERGE == grid[posStart.x][posStart.y]){vQueue.clear();vQueue.push_back(posStart);grid[posStart.x][posStart.y] = ST_TRAVELED;INT32 iIndex = 0;while (iIndex < vQueue.size()){const POS posCur = vQueue[iIndex++];INT32 dir;for (dir=0; dir<4; dir++){POS posNew = posCur + aDirection[dir];if (ST_SUBMERGE == grid[posNew.x][posNew.y]){vQueue.push_back(posNew);grid[posNew.x][posNew.y] = ST_TRAVELED;}}}if (iMaxSize < vQueue.size())iMaxSize = vQueue.size();}}printf("%ld/n", iMaxSize);return 0;}