[프로그래머스 Level 3] 정수 삼각형

function solution(triangle) {
    const m = triangle.length;
    const n = triangle[m-1].length;
    const table = Array.from(new Array(m), () => new Array(n).fill(0)); // ✅ Tabulation
 
    table[0][0] = triangle[0][0];
 
    triangle.forEach((siblings, i) => {
        if(i === triangle.length-1) return;
 
        siblings.forEach((node, j)=> {
            const prev = table[i][j];
 
            const left = prev + triangle[i+1][j];
            const right = prev + triangle[i+1][j+1];
 
            if(table[i+1][j] < left) table[i+1][j] = left;
            if(table[i+1][j+1] < right) table[i+1][j+1] = right;
        })
    });
 
    return Math.max(...table[n-1]);
}

function solution(triangle) {
    function calc(m){
        if(m < 0) return triangle[0][0];
 
        triangle[m].forEach((node, n)=> {
            triangle[m][n] = node + Math.max(
                triangle[m+1][n],
                triangle[m+1][n+1]
            );
        });
 
        return calc(m-1);
    }
 
    return calc(triangle.length-2);
}

function solution(triangle) {
    const m = triangle.length;
    const n = triangle[m-1].length;
    const table = Array.from(new Array(m), () => new Array(n).fill(0)); // ✅ Memoization
 
    function calc(m, n) {
        if (m === triangle.length - 1) return triangle[m][n];
        if (table[m][n] > 0) return table[m][n];
 
        return table[m][n] = triangle[m][n] + Math.max(calc(m+1, n), calc(m+1, n+1));
    }
 
    return calc(0, 0);
}

function solution(triangle) {
    const m = triangle.length;
    const table = Array.from(new Array(m), () => new Array(m).fill(-1)); // ✅ 초기값 -1로 설정
 
    function calc(m, n) {
        if (m === triangle.length - 1) return triangle[m][n];
        if (table[m][n] !== -1) return table[m][n];
 
        return table[m][n] = triangle[m][n] + Math.max(calc(m+1, n), calc(m+1, n+1));
    }
 
    return calc(0, 0);
}