leetcode-64-鏈€灏忚矾寰勫拰

Posted 2021-02-02

鏍囩锛?a href='http://www.mamicode.com/so/1/%e5%ba%94%e8%af%a5' title='搴旇'>搴旇   浣跨敤   鍥犳   鏁扮粍   浜岀淮鏁扮粍   min   涓ょ   璁捐   pre   

棰樼洰鎻忚堪锛?/span>

缁欏畾涓€涓寘鍚潪璐熸暣鏁扮殑 m x n 缃戞牸锛岃鎵惧嚭涓€鏉′粠宸︿笂瑙掑埌鍙充笅瑙掔殑璺緞锛屼娇寰楄矾寰勪笂鐨勬暟瀛楁€诲拰涓烘渶灏忋€?/span>

璇存槑锛氭瘡娆″彧鑳藉悜涓嬫垨鑰呭悜鍙崇Щ鍔ㄤ竴姝ャ€?/span>

绀轰緥:

杈撳叆:
[
 [1,3,1],
  [1,5,1],
  [4,2,1]
]
杈撳嚭: 7
瑙ｉ噴: 鍥犱负璺緞 1鈫?鈫?鈫?鈫? 鐨勬€诲拰鏈€灏忋€?/span>

瑕佸畬鎴愮殑鍑芥暟锛?/span>

int minPathSum(vector<vector<int>>& grid) 

 

璇存槑锛?/span>

1銆佺粰瀹氫竴涓簩缁存暟缁刧rid锛岃〃绀轰竴涓綉鏍间腑鎵€鏈夌偣鐨勪唬浠凤紝瑕佹壘鍒颁竴鏉′粠缃戞牸宸︿笂瑙掑埌鍙充笅瑙掔殑璺緞锛屽彧鑳藉悜涓嬭蛋锛屾垨鑰呭悜鍙宠蛋锛屼娇寰楄繖鏉¤矾寰勪笂鐨勪唬浠风殑鍜屾渶灏忋€?/span>

鏈€鍚庤繑鍥炶繖涓渶灏忕殑浠ｄ环鍜屻€?/span>

 

2銆佽繖閬撻濡傛灉浣跨敤鏆村姏绌蜂妇娉曪紝闄や簡鏈€鍚庝竴琛岀殑鍏冪礌鍜屾渶鍚庝竴鍒楃殑鍏冪礌閮藉彧鏈変竴绉嶉€夋嫨澶栵紙鍙充笅瑙掑厓绱犳病鏈夐€夋嫨锛夛紝鍏朵綑鍏冪礌閮芥湁涓ょ閫夋嫨銆?/span>

姣斿绗竴琛岀涓€鍒楃殑鍏冪礌1锛屽彲浠ラ€夋嫨寰€鍙宠蛋鎴栬€呭線涓嬭蛋锛屼袱绉嶉€夋嫨銆?/span>

褰撶綉鏍煎彉澶т箣鍚庯紝绌蜂妇娉曞お鑰楁椂浜嗐€傚洜姝ゆ垜浠噰鐢ㄥ叾浠栨柟娉曘€?/span>

 

瀛︿範杩囩畻娉曡璁＄殑鍚屽涓€鐪嬭繖閬撻搴旇灏辫兘鎯冲埌鍔ㄦ€佽鍒掔殑鏂规硶銆?/span>

鎴戜滑鐢ㄥ姩鎬佽鍒掔殑鏂规硶璁板綍鍒拌揪姣忎竴涓偣鐨勬渶灏忚矾寰勪唬浠枫€?/span>

宸︿笂瑙掔殑鍏冪礌鐨勬渶灏忚矾寰勪唬浠疯偗瀹氬氨鏄嚜韬€?/span>

鍏朵綑鍏冪礌鐨勬渶灏忚矾寰勪唬浠凤紝瑕佷笉灏辨槸宸﹁竟鍏冪礌鐨勬渶灏忚矾寰勪唬浠?鑷韩浠ｄ环锛岃涓嶅氨鏄笂鏂瑰厓绱犵殑鏈€灏忚矾寰勪唬浠?鑷韩浠ｄ环锛屾渶鍚庝袱鑰呬箣涓彇涓€涓皬鐨勶紝浣滀负鑷韩杩欎釜鍏冪礌鐨勬渶灏忚矾寰勪唬浠枫€?/span>

涓嶆柇鍦拌凯浠ｄ笅鍘伙紝鏈€鍚庡彸涓嬭鐨勫厓绱犵殑鏈€灏忚矾寰勪唬浠峰氨鏄垜浠墍姹傜殑銆?/span>

 

浠ｇ爜濡備笅锛氾紙闄勮瑙ｏ級

    int minPathSum(vector<vector<int>>& grid) 
    {
        if(grid.empty())return 0;//濡傛灉鐭╅樀鏄┖鐨勶紝閭ｄ箞杩斿洖0

        int hang=grid.size(),lie=grid[0].size();
        vector<vector<int>>record(hang,vector<int>(lie,0));//鍒濆鍖栦竴涓煩闃电敤鏉ヨ褰曟瘡涓€涓偣鐨勬渶灏忚矾寰勪唬浠?/span>

        for(int i=0;i<hang;i++)
        {
            for(int j=0;j<lie;j++)
            {
                if(i==0&j==0)//濡傛灉鏄乏涓婅鐨勫厓绱狅紝浠ｄ环绛変簬鑷韩
                    record[i][j]=grid[i][j];
                else
                {
                    if(i==0)//濡傛灉鏄0琛岀殑鍏冪礌锛屼唬浠峰彧鑳戒粠宸﹁竟鍏冪礌鈥滅户鎵库€濊繃鏉?                        record[i][j]=record[i][j-1]+grid[i][j];
                    else if(j==0)//濡傛灉鏄0鍒楃殑鍏冪礌锛屼唬浠峰彧鑳戒粠涓婃柟鍏冪礌鈥滅户鎵库€濊繃鏉?                        record[i][j]=record[i-1][j]+grid[i][j];
                    else//濡傛灉鏄腑闂撮儴鍒嗙殑鍏冪礌锛屽氨鍙栦袱鑰呬箣涓皬鐨勯偅涓€涓?                        record[i][j]=min(record[i][j-1]+grid[i][j],record[i-1][j]+grid[i][j]);
                }
            }
        }
        return record[hang-1][lie-1];
    }

涓婅堪浠ｇ爜瀹炴祴8ms锛宐eats 96.95% of cpp submissions銆?/span>