T1.网格中的最大乘积（11.22打卡）
网格中的最大乘积
- 题目
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- 解析
-
- 代码
题目
在下面这个 20×20 的网格中，对角线上相邻的四个元素已经用红色标记出来了，这四个数
的乘积为 26 × 63 × 78 × 14 = 1788696：
求在这个网格中，同一方向(上、下、左、右以及对角线)相邻四个元素最大乘积。
解析
要求：求网格中同一方向(上、下、左、右以及对角线)相邻四个元素最大乘积。
那就可以遍历数组，求每一行和每一列，斜左上和斜右上的四个元素的乘积，比大小求最大值
代码
public class chapter7 {
private static int[][] SQUARE =
{{ 8, 2,22,97,38,15, 0,40, 0,75, 4, 5, 7,78,52,12,50,77,91, 8},
{49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48, 4,56,62, 0},
{81,49,31,73,55,79,14,29,93,71,40,67,53,88,30, 3,49,13,36,65},
{52,70,95,23, 4,60,11,42,69,24,68,56, 1,32,56,71,37, 2,36,91},
{22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80},
{24,47,32,60,99, 3,45, 2,44,75,33,53,78,36,84,20,35,17,12,50},
{32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70},
{67,26,20,68, 2,62,12,20,95,63,94,39,63, 8,40,91,66,49,94,21},
{24,55,58, 5,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72},
{21,36,23, 9,75, 0,76,44,20,45,35,14, 0,61,33,97,34,31,33,95},
{78,17,53,28,22,75,31,67,15,94, 3,80, 4,62,16,14, 9,53,56,92},
{16,39, 5,42,96,35,31,47,55,58,88,24, 0,17,54,24,36,29,85,57},
{86,56, 0,48,35,71,89, 7, 5,44,44,37,44,60,21,58,51,54,17,58},
{19,80,81,68, 5,94,47,69,28,73,92,13,86,52,17,77, 4,89,55,40},
{ 4,52, 8,83,97,35,99,16, 7,97,57,32,16,26,26,79,33,27,98,66},
{88,36,68,87,57,62,20,72, 3,46,33,67,46,55,12,32,63,93,53,69},
{ 4,42,16,73,38,25,39,11,24,94,72,18, 8,46,29,32,40,62,76,36},
{20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74, 4,36,16},
{20,73,35,29,78,31,90, 1,74,31,49,71,48,86,81,16,23,57, 5,54},
{ 1,70,54,71,83,51,54,69,16,92,33,48,61,43,52, 1,89,19,67,48}};
public static void main(String[] args) {
int max=0;
for(int i=0;i<=SQUARE.length-1;i++){
for(int j=0;j<=SQUARE[i].length-1;j++){
// 同一行row，同一列col，斜向左上lTop,斜向右rTop
int row=0,col=0,lTop=0,rTop=0;
// 行
if(j+3<= SQUARE[i].length-1){
row=SQUARE[i][j]*SQUARE[i][j+1]*SQUARE[i][j+2]*SQUARE[i][j+3];
}
// 列
if(i+3<= SQUARE.length-1){
col=SQUARE[i][j]*SQUARE[i+1][j]*SQUARE[i+2][j]*SQUARE[i+3][j];
}
// 斜左上
if(j-3>=0&&i-3>=0){
lTop=SQUARE[i][j]*SQUARE[i-1][j-1]*SQUARE[i-2][j-2]*SQUARE[i-3][j-3];
}
// 斜右上
if(j+3<= SQUARE[i].length-1&&i-3>=0){
lTop=SQUARE[i][j]*SQUARE[i-1][j+1]*SQUARE[i-2][j+2]*SQUARE[i-3][j+3];
}
// temp记录四个中的最大值
int temp=Math.max(row,col);
temp=Math.max(temp,lTop);
temp=Math.max(temp,rTop);
if(max<temp){
max=temp;
}
}
}
System.out.println(max);
// 输出结果：70600674
}
}