【本文鏈接】

http://www.cnblogs.com/hellogiser/p/print-matrix-in-clockwise-direction.html

【題目】

輸入一個矩陣，按照從外向里以順時針的順序依次打印出每一個數字。

例如：如果輸入如下矩陣：

1???? ???????2??????????? 3??????????? 4

5??????????? 6??????????? 7??????????? 8

9??????????? 10 ? ? ? ? ?11?????????? 12

13 ? ? ? ? ?14 ? ? ? ? ?15?????????? 16

則依次打印出數字1, 2, 3, 4, 8, 12, 16, 15, 14, 13, 9, 5, 6, 7, 11, 10。

【分析】

解決這道題的難度在于代碼中會包含很多個循環，而且還有多個邊界條件需要判斷。如果在把問題考慮得很清楚之前就開始寫代碼，不可避免地會越寫越混亂。因此解決這個問題的關鍵，在于先要形成清晰的思路，并把復雜的問題分解成若干個簡單的問題。

通常當我們遇到一個復雜的問題的時候，我們可以用圖形幫助我們思考。由于我們是以從外圈到內圈的順序依次打印，我們在矩陣中標注一圈作為我們分析的目標。在下圖中，我們設矩陣的寬度為columns，而其高度為rows。我們我們選取左上角坐標為(startX, startY)，右下角坐標為(endX, endY)的一個圈來分析。

由于endX和endY可以根據startX、startY以及columns、rows來求得，因此此時我們只需要引入startX和startY兩個變量。我們可以想象有一個循環，在每一次循環里我們從(startX, startY)出發按照順時針打印數字。

【代碼】

C++ Code?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183

?

//?51_PrintMatrixInClockwiseDirection.cpp?:?Defines?the?entry?point?for?the?console?application. // #include?"stdafx.h" //?print?number void?PrintNumber(int?number) { ????printf("%d?",?number); } //?print?matrix?normally void?PrintMatrix(int?**a,?int?columns,?int?rows) { ????for?(int?i?=?0;?i?<?rows;?i++) ????{ ????????for?(int?j?=?0;?j?<?columns;?j++) ????????{ ????????????printf("%d\t",?a[i][j]); ????????} ????????printf("\n"); ????} } /* ??sx,sy--------------ex,sy ????|?????????????????????????????| ????|?????????????????????????????| ????|?????????????????????????????| ??sx,ey--------------ex,ey */ //?print?numbers?in?4?directions void?PrintNumbersInCircle(int?**a,?int?columns,?int?rows,?int?sx,?int?sy) { ????//?a[y][x] ????int?ex?=?columns?-?1?-?sx; ????int?ey?=?rows?-?1?-?sy; ????int?i; ????//?case1 ????//?sx,sy---ex,sy ????//?a[sy][i] ????bool?b1?=?sx?<=?ex; ????bool?b2?=?sy?<?ey; ????bool?b3?=?sx?<?ex; ????bool?b4?=?sy?<?ey?-?1; ????if(b1) ????{ ????????//?case1?matches?b1 ????????for?(i?=?sx;?i?<=?ex;?++i) ????????{ ????????????int?number?=?a[sy][i]; ????????????PrintNumber(number); ????????} ????} ????//case2 ????//?ex,sy+1---ex,ey ????//?a[i][ex] ????if(b1?&&?b2) ????{ ????????//?case2?matches?b1,b2 ????????for?(i?=?sy?+?1;?i?<=?ey;?++i) ????????{ ????????????int?number?=?a[i][ex]; ????????????PrintNumber(number); ????????} ????} ????//case3 ????//?ex-1,ey---sx,ey ????//?a[ey][i] ????if(b1?&&?b2?&&?b3) ????{ ????????//?case3?matches?b1,b2,b3 ????????for?(i?=?ex?-?1;?i?>=?sx;?--i) ????????{ ????????????int?number?=?a[ey][i]; ????????????PrintNumber(number); ????????} ????} ????//case4 ????//?sx,ey-1---sx,sy+1 ????//?a[i][sx] ????if(b1?&&?b2?&&?b3?&&?b4) ????{ ????????//?case4?mathces?b1,b2,b3,b4 ????????for?(i?=?ey?-?1;?i?>=?sy?+?1;?--i) ????????{ ????????????int?number?=?a[i][sx]; ????????????PrintNumber(number); ????????} ????} } /* print?matrix?in?clockwise?direction by?hellogiser?2014/5/23 */ void?PrintMatrixInClockwiseDirection(int?**a,?int?columns,?int?rows) { ????if(NULL?==?a?||?columns?<=?0?||?rows?<=?0) ????????return; ????int?startx?=?0; ????int?starty?=?0; ????while(2?*?startx?<?columns?&&?2?*?starty?<?rows) ????{ ????????PrintNumbersInCircle(a,?columns,?rows,?startx,?starty); ????????startx++; ????????starty++; ????} } void?test_base(int?**a,?int?columns,?int?rows) { ????PrintMatrix(a,?columns,?rows); ????PrintMatrixInClockwiseDirection(a,?columns,?rows); ????printf("\n"); } void?test_case() { ????const?int?ROWS?=?4; ????const?int?COLUMNS?=?4; ????int?a[ROWS][COLUMNS]; ????for?(int?i?=?0;?i?<?ROWS;?i++) ????????for?(int?j?=?0;?j?<?COLUMNS;?j++) ????????????a[i][j]?=?i?*?COLUMNS?+?j?+?1; ????int?*p[ROWS]; ????for?(int?i?=?0;?i?<?ROWS;?i++) ????????p[i]?=?a[i]; ????int?**array?=?p; ????test_base(array,?COLUMNS,?ROWS); } void?test_main() { ????test_case(); } int?_tmain(int?argc,?_TCHAR?*argv[]) { ????test_main(); ????return?0; } /* //case1 [3*5] 1???????2???????3???????4???????5 6???????7???????8???????9???????10 11??????12??????13??????14??????15 1?2?3?4?5?10?15?14?13?12?11?6?7?8?9 //case2 [5*3] 1???????2???????3 4???????5???????6 7???????8???????9 10??????11??????12 13??????14??????15 1?2?3?6?9?12?15?14?13?10?7?4?5?8?11 //case3 [4*5] 1???????2???????3???????4???????5 6???????7???????8???????9???????10 11??????12??????13??????14??????15 16??????17??????18??????19??????20 1?2?3?4?5?10?15?20?19?18?17?16?11?6?7?8?9?14?13?12 //case4 [5*4] 1???????2???????3???????4 5???????6???????7???????8 9???????10??????11??????12 13??????14??????15??????16 17??????18??????19??????20 1?2?3?4?8?12?16?20?19?18?17?13?9?5?6?7?11?15?14?10 */

【參考】

http://zhedahht.blog.163.com/blog/static/254111742010111112236313/

http://www.cnblogs.com/python27/archive/2011/11/29/2267975.html

【本文鏈接】

http://www.cnblogs.com/hellogiser/p/print-matrix-in-clockwise-direction.html

轉載于:https://www.cnblogs.com/hellogiser/p/print-matrix-in-clockwise-direction.html

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